Love or not is irrelevant. If a couple can live together till the end, it's success, even if they don't like each other 100% or even 50%. If you can tolerate a person for 40, 50 years, that is enough to prove everything. Most people would run off long before that, an average marraige lasts less than 7 years and over 50% ends in divorce.
The fact is no one can love another person as much as they love their own offspring. Because this another person started with you as a stranger and has no shared DNA with you. You love your children more than him/her because you gave birth to them and raised them up, that's a huge difference. So you choose to stay put partly because this person you chose before and whom you no longer feel in love with , he/she also has shared DNA with your children. Without this critical link, there's almost no other reason to hold onto a relationship or a marraige, even with the best intentions
Sexual love is for proliferation and reproduction. Once the goal is reached, or not ever being able to reach the goal, it's dead.
Dead to its roots.