Try oral, that always works.
Hhhmmm.... several ideas come to mind here: different positions, watching porn, going to a hotel so you are doing it in a different place, showering together and trying 'water sports', reading Playgirl, sexy dress-up, trying different types of lube or sex oils, purchasing sex toys. That's all I can think of. Let us know how it goes! Blessings - Blu
Maybe you got bored of the same penis in you . I've been with my bf for 3 years also , but I luckily still feel really good. ;D
maybe try new positions. Hopefully that helps . Good luck :)