We have a friend and he always invites this guy on our group nights out etc. This guy was never part of the friendship group and we struggle to find common ground and he can be boring. Our friend will not come out on his own with us unless this guy is there. Our friend sees this guy every weekend as they go to the cinema etc so I don't know why this guy needs to do everything with him.
We have suspicions they may be in a relationship as our friend is gay but if that is the case why not say. Though our friend has said before this other guy gets in the way of him catching up with us yet he still invites him out. I suspect he doesn't really want to hang out with us which is why he brings the other guy out as back up chat. I don't know what his motive is.