lost spark after 5 years dating

hey 7 cups community. I want to share my feelings and firstly, i am sorry if there any typos or grammatical errors bcs i am not native english speaker but i will try my best! :))

I think my fiance still cannot move on from his ex girlfriend which is his ex girlfriend is my friend. I feel like this because, my friend is his first love. they have been dating for like 2 years something during highschool and now we are 26 y/o. and also, they had romantically and sexually relationship. mind you, they did had sexually relationship but they not have a sex yet. his first experience with girl is with my friend so i think he cannot move on easily from her. Plus, last week my friend got married. and told you, my fiance seems so moody. he is happy go lucky person when he’s with me but last week, he looks so dull and moody. when i asked him, he said because of work. i don’t feel like he is moody because of work, but because her ex got married.

we already discuss about this and he said he already moved on a few years ago. when i bringing up this issues, he said that i am actually didn’t moving on yet.

so i don’t know what to do. am i wrong? am i overthinking? or is he still cannot move on but he puts the blame on me?