Girls, Girlfriend still friends (very very formally) with guy friend who likes her, red flag?

Have been dating her for two and half years, want to ask her to move in with me maybe i am scared which is why i am aggressively scanning for redflags before asking her.


College classmates, he his girlfriend (now ex), her (my girlfriend) were in some study groups, project groups etc due to similar classes/degree that is how they know each other. Now that guy had a girlfriend for the longest time, infact my girlfriend asked for his opinion and help while shopping for my birthday present (gaming gift that she had no idea about) he did not know it was for me by the way she doesn't really share much stuff with her friends anyways, not going too much into personal life unless she has known people for years sort of a introver that way. Same with her advising him what to gift his girlfriend on her birthday etc. These three also went shopping often

Now, this guy after breaking up with his girlfriend, asked my girlfriend out, which she flat out declined he sort of had some idea she likes me yet he asked that too 2 weeks after him and his girlfriend brokeup, anyways my girlfriend really didn't have much contact with him throughout the month and half long summer break. About two-three months pass we are back in college, this guy invites her to a house party, like everyone from their class was there, and asked her to bring me too.

My question is why was she still friends with him even though she know he likes her. Very formally though, they aren't friends now, after he said something nasty to her.

Girls, Girlfriend still friends (very very formally) with guy friend who likes her, red flag?
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