<human>: Summarize the given text in a few sentences.

So I started dating this girl (21F)a while back, and I lost my virginity to her. Going into that I had some issues with erections, nerves and whatnot. I solved that, or so I thought. Since I had no trouble really a couple times after that. Come this last weekend we were fine at night, but we went for another go the next morning and my downstairs brain was apparently just not cooperating. I am not a hugely sexually motivated person (sex is not a high goal for me, I enjoy it, but it is not a huge driver in my life). So I was wondering if that had much to do with it. I am also still pretty unfamiliar with the territory and figured that may be part of it. I dunno, she is super cool and has given no indication of it bothering her, though naturally I fear that it is bothering her. Does anyone have any suggestions or knowledge or insight or something?
<bot>: Had issues getting it up when first sleeping with girlfriend, overcame that temporarily, but it happens around half the time now. Have any tips?