Someone More Compatible

What would commitment mean with unlimited time to find someone better?

Nothing changes between a couple, but a compatibility ranking changes how they see their relationship. Someone could rank third for one person and forty-thousandth in return, with tiny differences. Does rank matter more than affection?

Over centuries, love could mean choosing again, accepting change, or knowing when to leave. Would a relationship need to last forever to have succeeded?

Endless life together could also be an unexpected gift from Death. What happens when forever stops feeling generous? If separation ends their lives, or their descendants' lives, where does love end and obligation begin?