My boyfriend thinks I'm still inlove with my ex - what should I do?

My boyfriend is with me for 2 years and till now he thinks I'm still in love with my ex of 2 years also,I'm getting tired and sick of him accusing me of that. Is the problem with me or with him?

What should I do to prove to him that I really love him only?

Note: I'm his first love in his life is that maybe why he thinks that way because he never got an ex before and doesn't know how it feels?
Updates
+1 y
I always tell him how much I love him and I never said before that I still have feelings for my ex because I really don't
My boyfriend thinks I'm still inlove with my ex - what should I do?
Post Opinion