I thought the sleep sex was used as a way of slipping past conscious emotional barriers that they had placed. I don't know that they would've achieved intimacy without by-passing those barriers near the beginning. Though, I thought at the time when reading it that there would no doubt be kerfuffles over this. Still, I was unbothered. I thought it worked in an almost (but not quite) metaphorical way.

And what I liked was that there was no 'good guy' and 'bad guy' in the relationship. Both did hurtful things. Both were hurt. Neither is really afforded the moral high ground here and has to accept. Yes, hurtful things were done to me AND I also did incredibly hurtful things to this other person. Then their learning that if they wanted a future together they had to find a way of working through and beyond that.

I liked that they were both flawed and -- almost despite themselves -- long loving (even when it would've made sense for either of them to have fallen out of love long ago.)