Boyfriend being distant

Me and my boyfriend have been dating for almost 9 months now but within the past week he has been acting differently towards me. We hangout a lot but whenever we hangout it seems like he's on his phone and always smiling at it which is weird. He just got in the shower and he usually leaves his phone on the charger but this time he took it to the bathroom with him to charge it. Also whenever we hangout I feel as if he's not really there with me like he's absent. I just don't know what to do because I've tried talking to him and he says everything is fine. I can't break up with him because I love him so much but he's just been acting weird and idk what to do. Any advice??