<human>: My girlfriend and I of almost 3 months (both 17) have only recently started to become sexually intimate; she gave me my first blowjob a couple of days ago. It started off very well, but I couldn't achieve an orgasm after 15 minutes, and I was some pain afterward for an unknown reason, and she felt very guilty even though it wasn't her fault. 
Today I tried to repay the favour by going down on her, again everything started well and we were both in the mood and after taking each others clothes off down to underwear, I was about to begin on her, but didn't. Major buzzkill. 
I think I wasn't ready (she is my first girlfriend and first sexual experience) and I was trying to force myself to do it while we had a rare opportunity of an empty house. 
The problem is that she believes the reason I bottled up is that I don't like her body; which is completely untrue. After constantly trying assure her that it's entirely my fault and not hers, she still refuses to believe me, meaning there's a constant tension between use. I want to make it up to her, but not only is she never in the mood, but she's also just started her period. So everything is incredibly precarious between us at the moment.

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: I said I'd go down on my girlfriend, didn't, and she thinks it's because I don't like her body.