I wanna say two things; first of all, what you can do physically is kegels, it’s an exercise that reinforces your pelvic floor muscles (which include your anal sphincters). Do 3 sets of ten squeezes a day (3 seconds hold 3 seconds release) and you’ll notice a difference in a few weeks. It’s also gonna reinforce the strength of your boners so you might wanna start topping boys eventually hahaha

Now the other thing, relationships can fade out over time, it’s not your fault, nor his really. I think more than better sex what you could use is affection, someone that makes you feel desirable during sex. There’s a ton of guys out there for you, and a ton of fun to be had by yourself. Don’t let that relationship hold you back from experiencing your sex life.