I know from experience just how difficult it is to pretend you are happy in front of your boyfriend when inside you feel your world is crumbling down... I've gone through similar experiences where I hide from my boyfriend but when it gets too much I tell him, which causes him to worry, which causes me in turn to worry that eventually I will lose him so I tell myself to bottle things up better next time, and I do, until the cycle starts up again and seems to never end... You are not alone.