I still like your idea

There is a lot of divorce, but those people go into the relationship at least looking for a life-long partner.

Those people are looking for something that they probably won't find. At least many exclusive pedophiles will admit that we probably won't find it.

I like the idea about future technologies being able to stop the age process completely. Then find some way to alter the brain using some kind of crazy nanotech so it makes love last indefinitely. You did say that it's nice to have a life-long relationship as a goal. Science and technology have been the best ways to solve problems in the past. Maybe one day we can finally transcend those limitations of love. We might have to wait at least two-three decades for that to happen anyway.