What am i doing wrong?!

So my boyfriend & I are in our early 20s & we’ve been sexually active for years, but lately its been very hard for him to...you know- get hard. I have tried EVERYTHING (besides viagra). I have been in my sexiest lingerie, given some of my best blow job work, and even tried building suspense. & NOTHING. Ive always thought we’ve been honest & ive asked him if hes been masterbating & he says no. & some times he gets hard, but then is right back to soft when we actually start having sex & it cant be my performance because its been fine years before but recently i feel like im failing as a sexual partner. We havent had sex in weeks and he still cant seem to get hard...we are both young and healthy so im not sure what it is...im honestly so frustrated & annoyed. PLEASE HELP!