I think this is right on. Unless the BF asks you about it or there is obvious evidence she is cheating, I'd keep it to myself.

However, I keep thinking of that line from Office Space:
Peter: I get the feeling Amy might be cheating on me.
Friend: Yeah, I get that feeling, too...:cool:

See, I think you need to be more specific about what being "hit on" really specifies.

If it was just a sleezy pass I would brush it off.

But, I once had a guy tell me he wanted me to take his virginity and he called it hitting on me....

I also had another guy who grabbed my breast and called it hitting on me........

Oh, and I had one smack my ass too....

So, yeah, I think specification is needed. ;)

SAI..i was leaving it broad just to kind of see what people would say :)

Ok...let's be a bit more specific....you all are at a party and the s/o in question says something to the effect that they have had their eye on you and and started aggresively flirting and even said something like "let's hook up sometime..just for drinks' but you can see that there may be more going on.......take it from there....

I used to date this girl and her best friend got drunk and hit on me pretty hard... I thought it was F-d up but also pretty funny.

One of my neighbors used to hit on me shamelessly. When one neighbor had a bonfire, he'd offer me a seat.. on his lap. He constantly asked where my kids were and, if they were with their dad, would say "OH, so you're ALONE" in that very obvious way. It was done in kind of a joking, overly sleazy way that I could blow off or joke away but I also knew that if I took the bait or gave him any indication that I'd consider it, he would go for it. I wouldn't do that to his wife. It was well known in the neighborhood that he cheated on her repeatedly. When he finally told her outright about one of his girlfriends, she kicked him out. I was relieved. I have still never said a word to her about how uncomfortable his overtures made me or how he was so obnoxious. She doesn't need more fuel on that fire and she's away from it now, so there's no reason.

did I like it? No, for real, in the moment I'd check the person about what they tried to pull. Later, w/out telling my signifgicant other, I'd casually inquire about how long/well they were friends.

If it happened again, I'd let my significant other know about it and that I'd had to check her girl's behavior earlier.