TL:DR I told my best mate he should leave his wife because she’s an alcoholic that will occasionally get wasted and make out with random dudes.

Background, we’re all mid 40’s, this is his second marriage, the first time around it ended because they just grew apart.
He’s been with Wife #2 for 5-6 years and they got married about a year ago. She’s a bit of a drinker, if anyone is going to get beyond wasted it’s going to be her. I’d say he’s a social drinker, will always have a beer with you, but is always the guy who is going to get you into a taxi when it’s time for you to go home.
Last night he confided in me that there’s a bit of friction in their relationship at the moment. While I knew that she gets quite lovely and will often hug you and tell you she loves you when she’s wasted, he told me that there’s been a few occasions over the years that he’s found her making out some random dude. I asked whether he thought it have ever gone beyond that and said he was pretty confident it hadn’t. He said each time he’s caught her it’s been when they’ve been out, she’s wasted and it looks to have been something that’s happened in the middle of the dance floor for a few seconds rather than being in a dark corner for an extended period. Each time he’s seen it, she’s been too wasted to remember that it happened. Apparently at University she had a bit of a reputation for doing similar all the time.
As a person she’s awesome, but she undeniably seeks out extrinsic validation. Everything is on Instagram and she’ll be the first one to tell you how great she’s doing, how amazing she is. He also told me that he finds it really awkward because she’ll almost make a point of telling him when she’s bumped into an ex-boyfriend, but will tell him he has nothing to worry about.
About a month ago she went out to a gig and ended up coming home way later than expected. At the time she told him that her friends wanted her to go to the after party and they were just drinking, chatting and hanging out because they hadn’t hung out for ages. A week later we’re at a party and she tells my Wife that at the after party she got chatting to the artist they had gone to see and he had propositioned her.  My Wife was shocked because she seemed stoked by the attention and seemed to be celebrating that this famous guy “wanted to fuck her”. Long story short, through one of our other friends this got back to my mate and he talked to her about it. He’s convinced that she didn’t do anything with the artist and that she told him the reason she was stoked was because she has recently lost weight, was feeling really gross and is now feeling good about herself and it was flattering to be noticed. He seems to think that it’s the combination of needing external validation and getting wasted that’s the problem and has asked her as a safety net if she’d curb her drinking and check in with him if anything changes when she goes out. She’s said that he’s trying to control her, that nothing has happened since they’ve been married and he needs to trust her.
Problem for me is that they go out a lot separately and because she’s kissed other guys when she was wasted and from all accounts will get wasted 7-8 times a year, it seems pretty unlikely that he’s been unlucky enough to see everything that’s happened.
I can tell that it’s really draining him emotionally, he seems really anxious when we’re out and she’s out.  
So I said that if she hasn’t changed and doesn’t appear to want to change, it’s probably happened more than he (or she) knows, worse may have happened and it’s probable rather than possible that it will happen again and likewise that worse is yet to come. I told him he needs to pull the plug and get out before it totally breaks him, because she will.

AITAH?