Hitting My Stride, and then Tripping

My own advice to myself about more conflict played off in spades when I finally got down 500 words that work for a situation at the very beginning, and from there I put together an outline for the first five or six scenes, up to the first time my characters have sex. I popped over 10,000 words for a minute, then dropped back down when I had to rejigger a scene to fit with the new outline. Plus I'm pretty certain, after doing a bit of research (I talked to a friend that owns a motorbike) that a scene I'd already written is physically impossible, so there's going to be a bit of change-around to do there.

It's always so depressing to be editing while you're still writing the text, like if what you already wrote has already collapsed under the weight of its own crappiness, how can you continue? Plus it seems a sort of weariness of the banality of the whole book, and the idea of it, has already begun to set in. How to keep such a repetitive thing (there's a constant litany of how much sexual attraction the characters have for each, plus what's keeping them from giving into it all the time) from getting dull while I'm writing it, and from getting dull for the reader? It's easier for the reader because everything moves much faster.