Wow. This is so not cool at all.

What I am guessing is the case here, is that she feels like you don't find her attractive anymore. I think she thinks that that is how erections work: you see a hot girl and you sport one, you lose it when you don't see someone you find attractive.

I suggest you sit her down and explain a couple of things to her:

• You still think she is attractive. If you feel it, I'd even say you think she is the most beautiful woman in the world, to emphasise it.

• Having or not having an erection has nothing to do with how attractive she is. You can sport random boners in math class with your 64 year old male teacher, or you can lose one while having sex with the most attractive girl in the world.

• You don't know why you lost your erection. You can assure her it's not because of her, maybe it's a medical thing, maybe you weren't so into it, even if you have no clue, this shouldn't be a big deal. Focusing on it like she has, however, raises the awkwardness and the pressure on you and little you, resulting in a harder (ironic choice of words) time having an erection for a longer while.

• It's unrespectful to be passive-agressive like this. You need to make this clear, right now. It's not okay to shame you for it. If she has an issue, she can talk about it. If she feels insecure, she can talk about it. If she was horny and you couldn't finish, there are other ways to get her off that don't include an erect penis, but she should talk about it.

If she can take these things seriously and maturely, you can work this through. If not, there is either a deeper issue going on, or she is simply not mature enough to handle a relationship.