Speaking from personal experience, finding the right relationship can be HARD. I recently came across a rational take on finding relationship partners, much of which really resonated with my experiences:
(I'm still working my way through the Sequences, and lw has more than eight thousand articles with "relationship" in them. I'm not promising the linked articles include unique information)
I think you're mistaken about how important sex is to relationships, This varies pretty wildly by individual, but I find it easy to believe that a good portion of the populace would be better off if there were many uncomplicated orgasm sources, rather than requiring a deep committed exclusivity.
That bundled commitment is valuable, and I'm quite happy in it. And, over time, as technology improves and my wife and I age and change, I can easily believe we'll add robots to our marriage. We have some now, but they're mostly there for mechanical assistance, and we don't have much of a deep bond with them.
Speaking from personal experience, finding the right relationship can be HARD. I recently came across a rational take on finding relationship partners, much of which really resonated with my experiences:
http://waitbutwhy.com/2014/02/pick-life-partner.html
http://waitbutwhy.com/2014/02/pick-life-partner-part-2.html
(I'm still working my way through the Sequences, and lw has more than eight thousand articles with "relationship" in them. I'm not promising the linked articles include unique information)