I feel broken

So this is topic that's very personal to me and I'm just looking for some kind of guidance.

Whenever ny boyfriend and I have sex I can never finish and recently it seems like he's put a lot of effort into sex to get me there. It feels amazing but recently I was on the brim of orgasming and just broke down into tears during sex because I-just-couldn't. I feel awful that I can't and I don't know why. I want him to be there when I do it because it's personal and I just love him so much. I'm able to do it by myself. I just feel very broken and unwomanly right now because it's so embarrassing.