guy im dating

we've been dating for 4 months now and his energy is always down, it makes me feel like hes not interested. he disagrees when we twlk about it. he claims that it because he doesnt quite trust me.

a few months ago a guy friend randomly text me when i was out with my date and ge saw when i opened it, so ever since he claims he cant trust me.

this whole thing sucks because i see a lot of potential except this is blocking a lot... what should i do? ive explained to him that im not interested in that person and that i can have friends if i want to...