Can't finish with partners

So I've been like decidedly active for a few years but I've never had a guy that's been able to make me finish and I feel like something is just wrong with me. I'm in a pretty new relationship with another guy and I don't want to tell him about it incase it annoys him or he gets insecure (my last boyfriend blew up at me for not being able to finish with him so I'd fake it to avoid the argument or him making me feel bad, which is why I just avoided telling anyone else I was with). If anyone has any advice or something I'd be so grateful.