FWIW, I call this scenario “The catalyst consumed by the reaction.”
A couple is dating…things aren’t going great. Maybe he takes her for granted or proactively pisses her off.
At this point, she may call him and say: “I don’t know if this is going to work out” or make other grumblings about the relationship. But there’s an inertia, possibly fueled by empty threats or indecision, etc. Maybe he gives some lip service but nothing happens.
To her, the grass starts looking mighty green on the other side, and a situation like the one you describe comes up. So she jumps the fence. Intense makeout, love is so wonderful, yadda.
At this point, she may call him and say the very same words: “I don’t know if this is going to work out” or make the same other grumblings about the relationship. But this time, it’s different. Maybe it’s her tone of voice that lets him know, ‘Wow, she’s not fucking around this time!’ Because after all, she’s emboldened with the knowledge that she can kick him to the curb…you’re already in the bullpen so there’s little uncertainty in her mind, which she subtly conveys whether she’s trying to or not.
Or, if she’s seen him in person, maybe it’s the expression on her face. Or maybe it’s that she calls faithfully every night at a given time and suddenly it stopped. It could be soooo subtle that the conscious mind can’t detect it, but his subconscious knows good and well that something has changed.
So at this point, he REALLY listens to her and like most people, his reaction will be “Baby, come back! I didn’t mean it! We can make this work!” etc. And he means it. For awhile, at least. Long enough for you to be harpooned through the heart, anyway.
You catalyzed a reaction for them and then…well, where are you in that beaker?
Backtrack: some would get high and mighty and say, “Shame on you for messing with another man’s woman!” Well, ok, maybe, I don’t know. But I’ve long suspected that what we call “morals” or “ethics” are really shorthand for the most practical way to live.
I.e. yes, he doesn’t deserve her, and yes, if she were truly happy with him she wouldn’t be vulnerable to you, etc. All the academics aside, it’s worse than not getting the girl…it’s knowing that you started a chain reaction that blew up in your face.
I really do sympathize with following your heart…and I hesitated to post some of this. But when I’ve been burned, I’ve always forced myself to learn from it. The only thing worse than going through some things is going through them twice.
My advice? I think you’re already screwed. I’d lay low, let her call you. But I think she’s already gone back to him—in her heart if not in the flesh—when she’s asking that you meet in a public place etc.