After playing with several cover bands during my high school years, i have come to the conclusion that at most times, in my case, good friends doesn't mean good band members. I have played with close friends who end up not co-operating with band members and they are usually the other guitar player or the drummer. The bassist is always the cool cat
But when i play with another musician that i barely knew, we can work together in the studio easily although we are not close outside the studio
The thing i hate the most is when the rhythm guitar player tries to "take over" the lead guitarist's role in the band during a session or rehearsal. I mean i don't mind backing off a little bit, but at least try to communicate instead of just giving the cold shoulder