This is important. I think most men don't realize that this is a massive red flag. Don't get me wrong, I think it is VERY important for women to have other women friends and get together. If you tried to keep your relationship chick away from her friends, you will drive her nuts... and she has every right in the world to dump your @ss.
But women can get together and have coffee, or book reading clubs, go shopping, any number of BS chick-sh!tlike activities. But if she's having "girl's nights out", that doesn't just involve going to some half-@ss chick flick, or dinner at some cr@py vegan restaurant, that you don't want to go to anyway, your 'relationship' is in trouble. Now if she starts doing this sh!t.... there isn't a fvcking thing you can do about it accept walk away. But if you think you can fix this and hang around... well, my advice would be to make sure she brushes her teeth and rinses out her mouth before you kiss her, after a night out drinking with 'the girls'.
I don't mess around with married, engaged, or chicks with live in boyfriends. I don't do this because I'm a paragon of moral virtue, God knows, I do this because I don't want some psycho jack@ss coming after me, or get drug into divorce court because this chick can't control herself. However, 3 times in the last couple of years I hooked up with three married chicks. I had no idea they were married, and as soon as I found out I broke things off. It would happen a lot more if I wasn't careful... I don't even remember how many times some relationship or married chick was giving me the green light. THEY ARE ALL LIKE THIS. It's not just the promiscuous ones, it's ALL OF THEM. Under the right set of circumstances, and if the timing is right, ANY chick will cheat on her man. It's just happens a lot more, and sooner with ones that have a history.