He doesn't trust me 😡

Am
I was telling my partner about my new sorta friend who has been messaging another man sexual things and is in a relationship. He also sent her pictures (she told me this) He then turned on me and said well she's trouble, I bet she's shown you the pictures and how do I know when you guys are out and your trying to impress her you won't say aw that guys hot and flirt with them etc etc.. I am like.. wahh? This man is the love of my life and we are engaged. His ex cheated on him and I am so annoyed that he would even think that way about me. I have never done anything wrong and try to reassure him but sometimes he gets so stuck in his own head. I'm really pissed off.. don't know what to say or do 😡