How much time did they spend together BEFORE the separation just hanging out together and talking? When I was young I VERY rarely hung out and talked to my dad. We just didn't have that kind of relationship. If my parents had separated (never any problems that I knew of--strictly hypothetical) I'd barely notice his absence, other than not seeing him at dinner. It wasn't tense/hostile, just the way my dad is.
I wouldn't worry about it, TBH.