Partner not making me cum

I’ve been on and off with my partner for a while and we recently got back together and anytime we have sex, I am unable to finish. He tries to finish me and got vibrators and dildos but I can’t seem to finish at all. It’s kinda hurting our relationship cause my partner is a kind of guy who likes to make sure I finish before he does. We have done foreplay and everything, I just don’t know what to try not ... please help !