**** that I'd be like "ima sit back, and let you show me how it's done!"

There is a solution to your problem. I'll give you a hint: it starts with a B and ends in 'lowjob'.

I am pretty sure most guys get nervous the first time and can't keep it up. Tell him that it's completely normal :)

Little-known fact: Erections are closely related to goose bumps. In either case, a "valve" opens up and allows blood to flow into chambers that normally have no blood in them, and the blood pressure in the chambers causes either the hairs on the skin or the penis to become erect. Here's the point....although you generally know what kind of things cause goose bumps, nobody expects anybody to be able to get goose bumps on command -- and yet, we expect men to get (and keep) erections on command. Both men and women need to understand that they are NOT a voluntary response. Patience, understanding, relaxation and arousal are the keys. Tensing up and getting nervous about it are nothing but counterproductive.

Maybe he wants you to rape him. :p Kinky stuff

The physical has turned emotional. Instead of trying to get him in the mood you need to have a heart to heart with him. Tell him it didn't bother you that that happened. That you know he's embarrassed but he doesn't need to be. It happens but you want to be intimate with just him. There's lots of factors for why this happened and that it's ok. You need to caress his ego before caressing his penis.

He's probably cheating on you

He needs to get right back on that bicycle and ride like the wind.

at least it has nothing to do with you OP =)

I suppose he couldn't rise to the occasion.