For a variety of reasons, the least of all being his reputation, this is not a good idea. Professor-student relationship are more common than many of us probably think. The rumor mill is definitely there. One of my professors went through a similar situation in marrying one of his former students. Many other members of faculty, shall we say, hinted their disapproval, but by virtue of his seniority within the department, and the fact that he was one of the most liked professors on campus, the issue was a non-starter.
Methinks you are "the other woman. Except that you are the other woman. If he breaks up with his girlfriend on his own, fine, but don't go planting ideas in his head.
If you really do love him, trust him to notice if his current relationship is making him unhappy. Poaching is never, ever a good idea. Were he single, this would be a totally different matter, but all issues of reputation pale when the question is actually, "should I try to break up someone else's relationship based on a chemistry I perceive? And if you've hung out and chatted and emailed as much as you apparently have, and he hasn't indicated that he'd like to make mad, passionate love to you, etc etc That aside, I would be leery of getting involved with a man who lives with his girlfriend.
Aside from the ethics involved - but, frankly, how can you leave the ethics of this aside? If he were single, I see no particular problem with someone dating a former mature student. If you were 19 when you were in his class, I think it's a little murkier, but if you were anywhere in your 20s, I wouldn't find it bothersome. However, I know someone who married her professor, and I do have the impression that people talked about it a lot, and that it wasn't and isn't always pleasant, particularly for him.
PS, can I tell you something, one girl to another? Don't fall into the trap of thinking that his girlfriend is an evil witch and bad for him and treats him terribly. That's not sisterly of you, man. Am I supposed to bow to the altar of the live-in relationship?
Pack your bags, don't let the door hit you on the way out. And to call it poaching? If anything, the professor would be the poacher. In any case, I think the OP was just trying to be clear about the details, not to hear your harp on hurting the other girl's feelings.
People do this all the time, so I'll be the last person to say "this is always and in all circumstances against the rules! He didn't leave my Mom for her. She is super nice. She's been my stepmom for almost a decade. I have no idea if any of this applies to you and I don't know you from Eve, but if you make the moves on a guy with a live-in and start having a committed non-fling relationship with him, you may ultimately find happiness, but you can't escape being "the other woman" and it's not unlikely that you may find yourself on the reverse side of the occasion at some future possible point where you are the long term live-in girlfriend and someone else is the hot younger student.
You're no longer his student; you're not even at his institution. There's no ethical issue with you two dating. I've known people in similar situations, and while there will always be gossip, it's certainly not perceived as "horrible".
That said, I think there might be other, bigger, problems with your plans here, as other answers have pointed out. I think that's a good point, but I also think those circumstances of the relationship and its inception are going to have a big impact on how the rumor mill responds to this. If it's something that a lot of people here think is a questionable move, then there's a pretty good chance of colleagues being less than charitable Look, he already has a serious, live-in relationship regardless of your presumptions about the quality of that relationship, and regardless of the chemisty the two of you may very well share -- worrying about the damage or lack thereof to his reputation if the two of you start dating is pretty low on the list of main issues right now.
If they break up -- and that would be their choice, not yours -- and if you and your former professor seem to then be in a place where you would mutually like to start a relationship, then you deal with the issue of his reputation. And I personally think dating a former student shouldn't do much than briefly raise a few eyebrows.
I am thinking of saying something, but not sure how. I'd hate to be thought of as "the other woman" but I would like to communicate a bit of how I'm feeling.
Sorry, you can't have it both ways believe me, I speak from experience: I once faux-innocently "said something" to a male friend who I had a crush on about his obviously failing long-term relationship, and it became infinitely more complicated and painful for everyone involved than I could have ever imagined. Either you insert yourself into their relationship as the other woman even if "just" emotionally and potentially reap the whirlwind, or you don't.
Again, if your former prof breaks up with his girlfriend, and if things start moving along from there, great. But don't actively stir the pot! I know you're hoping that by just "saying something," you'll set in motion the course of action by which he breaks up with his girlfriend and starts dating you instead, right?
But even putting aside A the ethics of being the other woman, B his reputation due to dating a former student, and C the complex situation that you may unleash that's not going to be fully within your control, that's rarely good footing for any relationship to start on. I've seen several profs who have dated former students I don't recall if any ended up marrying said students , as it happens all male profs with female students.
In some cases, they got together when she was still a student, in other cases, no one knows, but in every case a lot of people really suspected, given what happened later, that he had been sleeping with his students.
So realize that even if you're not doing anything wrong like that, many people will assume you did. That's just the way it works. On the other hand, nobody I'm thinking of got fired over their relationships, even the one who did date a student. It's good to have tenure, I guess. Just because you're attracted to him does not mean that he's attracted to you, even if you have the chemistry to make great friends.
And by the way, it is really awful of you to think about ruining someone else's relationship. Would you want someone to that to you? Have you ever been cheated on or had another woman very obviously try to steal your man? I bet you haven't. If he was single, then it would be a completely different story, and no it wouldn't be much of an issue for him to date a former student this happened while I was in graduate school between a prof and former student - they're married now, actually posted by echo at I don't think his colleagues will give much of a shit.
I know it from both sides. Some profs even like the reputation, especially if they have tenure and are careful not to cross any technical lines. Sometimes just being a flirt which your man may well be does the trick.
But that isn't the real question, as everyone is saying here. He could be a lumberjack, but he's still off limits unless you want the non-career-specific hell you'd be buying for all concerned. And you don't need anyone to tell you so if you have any experience in life. Then stay the hell away. In that case whatever rumor mill there is might not be as harmful to him professionally.
But I still would not go around presuming anything about his current relationship. I mean, how much do you really know about the nature of their relationship? How much of your perception of their relationship owes to your own interest in the professor?
That being said, one of the major pieces of gossip amongst the undergrads at my BS institution was the relationship between two of the professors, which had begun while one was a student. Today, it isn't an issue for faculty or staff, but the male professor was the type that really couldn't care less what his colleagues think of his personal choices.
I think that it won't matter in the slightest once you're not an undergrad in the eyes of the community e.
More relevant might be the fact that he's dating someone already. However, the fact that you were previously his student is NOT one of them. That is now irrelevant. Most of the long term, happy relationships that I'm privy to are between people who, on the surface of it, seem to have nothing in common.
Bad for his career. This is how affairs happen between women and men who do not intend to leave their partner. This is how it starts. This is an old, old story. If he's 55 and you are 23, people will notice that. Is his girlfriend in the same discipline as you, or even just an academic in another field?
If so, this is a bad idea, especially for him. This would be shitting where you eat. Are you going to grad school in his field? If so, any relationship you might end up with will be doomed to very severe inconvenience.
Life is very hard for dual-academic couples, especially when they'd be in the same department. If you go for it and everything goes swimmingly and it's Prince Charming and Cinderella happily ever after, expect that either you will live apart for a very long time, or one or both of you will have to make very serious career sacrifices so you can both work in the same metro area.
Men in relationships will sleep with other women without any intention to start a relationship with them. It's trivially easy to seduce a man. But you will find that the fallout will destroy everything that has taken so long to build up.
Find another boyfriend and let the prof be. By sleeping with him, there will be 3 victims. And even more especially if his not-currently-ex is in your field. He is an established scholar in the field, which presumably is what you would like some day to be. But if you hook up with him and cause him to dump his live-in partner, you will not be introduced to others in the field as a scholar.