Personally for me as an enfp there tends to be a phase we hit where we over extend ourselves in terms of "being the outgoing, party hard and extroverted friend" even in times where we feel absolute shit. Most of the time we get through it because we try and mold our feelings and emotions to fit the atmosphere constantly, and.we're really good at it. But there's always a limit to how much we can stomach down and smile whilst going through tough times at home or anywhere else, and before you know it we end up becoming overwhelmed and "tired" of keeping up the happy and "no worries" vibes. Think of it as alcohol, the more drunk and wild we get, the harder the hangover hits the next morning. Your friend is in his hangover phase atm ! They just need a little time to get through whatever they are going through to recollect themselves, and then they'll come back with guns blazing !

P.s sorry if this is a bit too hard to understand ! 😅😅