What do you guys think about this?

My best friend was talking/ messing around with this girl for months, she also has a bf. Now idk if they have an open relationship but he lives in a different state. Sometimes she flies out there and will stay for a couple of weeks and vice versa. My best friend started to fall for her hard and she would tell him that she’s going to break up with her bf so they can pursue something but would never do it. Instead she would post pictures of them and how much she loves him. She looks single she’s always going out with her girls and hasn’t posted him for awhile. Well they had a falling out because my best friend actually moved on and when he was with his (now ex) she called him at 3am drunk of course his gf at the time got mad. He completely cut ties with this girl but when he’d have problems with his gf he’d add her again. Anyways.. long story short him and his gf broke up and he started to talk to that girl again. I’m just afraid she’s going to do the same thing to him and string him along.

He swears that she’s changed and she claims she wants to see where they can go from here.

Idk if she’s still with her bf. I don’t care to ask q’s he just tells me what he wants.

She’s 27 hes 26,

Edit- no her bf never knew that she was messing around with my best friend.

Because one day we actually bumped into them and she introduced him as a “friend” the guy looked completely clueless

Edit- for the person who said it isn’t my business uhhh he’s making it mine by telling me all this drama and asking for my input.

That’s why I wrote here because I don’t even know what to tell him