not horny

So I always want sex. Sometimes I think more than my boyfriend but the last few days I haven't been feeling it. Today I was enough in the mood that we started having sex. But I just couldn't get wet like I usually do like it's usually a waterfall down there. I felt like I was failing at sex and it was frustrating. I started to cry and I just feel so defeated right now. I don't know where I'm going with this.