Background Information: We have been together for 2.5 years. We do not live together, but visit each others apartments around 5 times a week. He is in his early 30s and I am in my mid 20s. We live in Germany
Story:
A few month ago I found a picture of my boyfriend kissing (what I assumed was) his ex girlfriend while looking for some stuff. I did not think much of it, and put it back.
My boyfriend has many pictures hanging in his apartment, most of them are with his friends, a few are with myself.
I suddenly noticed that one picture (not a group picture) had his ex girlfriend on it. It was just her on it. Alone.
When he came home, I asked him if he would mind removing her picture. He said "I can do that".
Fast forward a few month. The picture is still in the frame, I asked him again, because maybe he just forgot. "Sweety, could you please remove her picture, I really don't like seeing it." He answered: "good you didn't see there are actually two pictures of her, but sure I can remove it"
I was kinda speechless. I know he does not try to be mean, and I know he does not love her anymore. But the picture still hangs there.
Question: How do I tell my boyfriend how much I want these pictures gone, and that this task is not something he can postpone any longer?
Clarifications from comments
I explained to him why I was bothered by the picture. To be honest my only reasoning was that she is really pretty and that she is his ex who cheated on him and that I do not want to see that kind of person in my daily life.
I haven't asked why he has not removed the pictures yet, despite him saying that he would. I just thought he forgot. He is the kind of guy that leaves stuff he does not deem important for a long time. Example: All he wanted for christmas (2years ago) was a huge Lego Star Wars set, well he did not open it until now.
I actually never have made a conscious attempt to push him to do something faster. I am not really sure when he chooses to procrastinate, and when he is doing something immediately. Even things he really enjoys like riding the motorcycle, have to wait sometimes, because for example he doesn't replace something that needs repairing. Maybe his job is just very demanding and he feels like doing nothing in the evening.
I'm sure this person is his ex girlfriend. I have not "asked", but I stated it to him and he agreed. Also he is not that kind of guy who would randomly kiss a girl for pictures, and keep those in his apartment.
UPDATE:
Thank you all for your help and your insight! I did talk to him yesterday evening while walking from the car to his apartment so he wouldn't be distracted by anything. I used "I feel" statements like recommended by Noah Goodrich. And I also used the firm approach Mister Positive recommended. It went well, we removed the pictures together and added different pictures. He threw the old pictures in the trash, even though I told him he doesn't need to. Then he told me he loved me and gave me a kiss.
After so many people in the answers and comments told me how wrong I was for not wanting these pictures up there, and that I need to ask him for reasons I also asked him for his reasoning for keeping them up for so long. He told me it was just laziness because the frames are so difficult to open. I just wanted to add that I think it is sad how many people think my relationship is as temporary as his other relationships. We are planing on rebuilding an old house together and talk about marriage and children, I deeply hope you are all wrong.
Thank you again!