Nothing. It’s a song. There is nothing that your current boyfriend can do with the fact that you have a memory with an ex. It’s life. We all have them. I have them. The point is to see it as a memory only and keep moving. As long as you aren’t throwing the song or any memory in his face, he will be okay. He may just be upset because he feels that another man has shared something he hasn’t. My thing is that is the way dating works. You will never really share everything with one person. There is space although small that we all bring in from someone else. It’s no different from a cologne or perfume smell. It’s all a memory. It reminds me of the song by Jill Scott, “Cross my mind.” In the song she talks about a memory in the form of her ex’s cologne and she attempted to have the next one smell like the last but it stunk. Everything isn’t for everybody. It really isn’t. Your boyfriend has memories of other women he just happened to know about one of yours and it stung him a bit. He will be fine. Let him know that there is nothing to be worried about and let that be that.
To the part where you should stop singing unless you have a mic or a made up mic and are literally in his face with it, he will deal. Songs come on. I know of one of my husbands songs for his ex and I just mention it and move on. I have songs for my exs and it is what it is. I don’t sing it like I am attempting to make American Idol but its a memory good or bad and it fades.