He keeps stuff from his ex's on display at home?

I’ve been dating a guy for a while. Things are good, but there are some things that has made me apprehensive.

He has talked a lot about his ex’s from the very beginning. Details I’m not really interested in. Holidays they did together. How they met. Even humble bragging about his stamina in bed and how satisfied they were. How devastated they’ve been when he ended it with them, saying they would never meet a man as awesome as him ever again. It’s just so unnecessary.

I’m also surprised by some things on display in his apartment. Firstly, he has a lot of things pinned on the walls, from concert tickets and drawings from his children, to travel memorabilia and art posters. All well so far. But then there’s so many postcards, letters and notes on display. Not just from friends and family, but from former girlfriends as well!

In his kitchen and living room there’s quite a lot of love notes from his ex’s and at least two long letters from a close female friend of his who’s obviously quite smitten with him. I asked him about it and he confirmed that she is indeed in love with him, but that she knows it can never be more than a friendship between them.

In his guest room and home office there’s a photo calendar on the shelf of him and his ex from a few years back, which she made for him. On the wall I saw at least four quite intimate love letters from former girlfriends. Everything on display for everyone to see! He told me recently that he loves me, which I thought was quite early. He claims he hasn’t said it to anyone before me. But on one of the letters on display, an ex writes how she appreciates the way he tells her that he loves her!

The only room free of ex related memorabilia is the bedroom. In there he’s keeping a couple of cards that I’ve given him and a gift from me, and he’s even printed and framed a photo of me and him on his night stand. He says he keeps the things most precious to him in the bedroom.

He seems to be serious with me and has moved the relationship quite fast. I’ve even had to put on the brakes a few times. I just don’t understand the need to decorate his walls with things from previous ex’s?

Today we had our first argument, because he thinks I don’t make him enough of a priority. I was staying the night and thought we had resolved things before we went to sleep, but then he woke me up at the break of dawn because he was still agitated about it. After we’d talked for a while he got out of the bed, and placed a cup with an inscription in my hand. Turned out it was a gift from a female friend whom he used to work with. He hadn’t seen her in years but visited her a couple of weeks ago when he was in her home town for work. From the inscription, it’s clear that she has romantic feelings for him. He said he didn’t knew about her feelings for him. I asked him why he showed me the gift, and he said that some women really appreciated him and would love to be with him. It made me beyond frustrated.

Of course, now I’ve only mentioned the things I don’t like about him, but I think it’s quite concerning. We’re supposed to have a dinner date tomorrow, but I feel uneasy about it because of the things mentioned. What should I do?