Bf obsess with half naked models

Mandy
Idk how to feel about this , it's constant liking other women on Instagram and following them and also screenshots them. Half naked beautiful girls ,, am I not fulfilling him , I want to end it because he doesn't even show he's in a relationship or posts pics up of us... I feel like he'd rather be with one of them.. I know would probably be impossible but idk.. Yes I went threw his phone and he's got nothing but screenshots of all these women .. Idk how to feel anymore and it makes me upset ..