We already have sexbots that are the size of genitalia, and even people who like them prefer other people as well.

I don't. I'd classify sexbots into two types. Ones that aren't people, so they won't be emotionally sufficient to compete much with real women, but exploiting them is fine. Ones that have been improved until they are people, in which case why not love them? Human diversity makes a species-wide rejection of human-human relationships unlikely.