Sure. It may sound weird in the abstract, but in practice, it's perfectly normal. Imagine you're out, you meet a woman, and ask her out. She says:
"Look, I've got a boyfriend, but we've been going out for 8 months and he won't commit. So I told him that if another guy asks me out, and I like him, I'm going to say "yes", and see what happens."
Now maybe that would be a turn-off for you, but not for me. Because if you get to the point where you're really hitting it off with the girl, she's going to ditch that other guy.
I don't have a problem with that.
In that example. If she cheats WITH you, she will cheat on you.
If she’s upset that her boyfriend of 8 months isn’t proposing or at least talking serious proposal (shopping for rings, setting dates etc) then she should just break up with him.
Using me as a way to get her “boyfriend” to propose is dishonest on all sorts of levels.
“Look, I’ve got a boyfriend, but we’ve been going out for 8 months and he won’t commit. So I told him that if another guy asks me out, and I like him, I’m going to say “yes”, and see what happens.”
OK, I can understand that, but will take your case a little further.
She says “Yes”, and you go out, and you like her, but under our original premise, you won’t be sleeping with her, certainly this time, and again, not until such time she breaks up or changes the nature of her relationship with Mr. “Right” of eight months.
So afterwards...
She’s slept with him before, and is still in a sexual relationship with him. Will she tell him of her date with you? An honorable woman would. Will he try to win her “back”, or away from you? Will he initially be successful and have sex with her again, until THEN she (perhaps) decides she wants you instead?
Lots and lots of variables all out of your personal control. Not that I’m making this a control issue, just that you’d be leaving your feelings entirely in the hands of the woman who has a boyfriend, but has decided, for some reason or another that she may or may not fully understand herself, or truly told you, to go out with you at least once.
(Perhaps she’s hoping a date with you will get him serious?)
Who knows.
Obviously, I’m not for it, but I respect your opinion.