
That's not a weird thing to say at all, and I'm sorry that's going on! It must feel strange to see him seeming uncomfortable by the compliments. It sounds like he may be struggling with a lot of self-esteem, which is tough, and I'm really sorry he is. You can do your best to be supportive about this but ultimately, it's something he has to work on and he may benefit from talking to a professional about it
He’s insecure (we all are) you have two options here. Either figure out his love language so he really does trust you and then believe you, or you might have to end it. I’ve been there and a few relationships blew up in my face bc took me a while to get real confidence. When one of my ex’s really made me trust her by showing my love language (physical touch and just not openly getting into the details of our relationship with her friends) I started believing her.