F-24 M-22 , Overthinking or there's smth fishy

My partner of 2 years has become emotionally distant and always says work is demanding or he's tired.

Yesterday, I simply asked for his phone to order food, but he refused, changed the subject, and seemed scared to hand it over. I never accused him of anything, yet he brought up cheating himself, saying, "You don't actually want to order food, you just want to go through my phone because you think I'm cheating."

After that, I asked him about a girl he had recently followed on Instagram. He denied knowing her, said, "I don't know how I followed that account," and later removed it. This has happened before with the same excuse. Now he's calling me crazy and saying I'm only overthinking because my ex cheated on me.