Feeling Rejected By my boyfriend

Me and my boyfriend have been together for roughly 2.5 years. Within the past 6 months sex has greatly diminished. He gives me kisses on the cheek but is rarely intimate or even gives cuddles. I feel rejected. He says he just doesn’t want sex or is tired. We are together all the time and he lets me check his phone and everything. We live together. But idk what to do ? I’ve expressed how I want Sex but he just doesn’t seem interested in me.

Please send positive messages or advice sister is struggling over here!