I try not to define love.
I think it depends on the situation.
Sometimes; love is holding on. Sometimes it's letting go.
Sometimes love is giving a gift. Sometimes it's accepting one.
Sometimes love is a feeling. Sometimes it's an action.
Sometimes love is a passion. Sometimes it's a soft consideration.
Sometimes love is making a mess. Sometimes it's cleaning one up.
As for relationships;I think I might define them different than you use here as well.
To me-a relationship exists anytime a connection is made. Regardless of depth.
So for example; you and I have a relationship. Because we have communicated.
My ex-girlfriend and I have a relationship (even though we only talk maybe once or twice every few years) because we have met and know each other.
Also-I love her. Loving her, means leaving her alone most of the time. Once in awhile it means letting her know something special is happening that she might want to be involved in with the girl-child she helped me raise.
Mostly it means respecting her need to not be a major part of my life.
But, loving GG means being available to him daily, giving him hugs and kisses and sometimes reassurance. Exactly the opposite thing that my ex needs from me!
Both I love-and in both cases I am actively loving them by my choice of actions. But the actions are polar opposite.
Have you ever read "The seven levels of intimacy"? It's a great book. It's kind of similar in how I see relationships. I don't see relationships as being static or definable.
GG and I are friends. Sometimes we are lovers. Sometimes not. We have been FWB. We have been FB. We have been bf, we have been best friends. We have been roommates. I have been his boss. We have been coworkers.....Sometimes we hang out a lot. Sometimes not. He is a best friend. He is a pain in the ass. He is a friend. He is a boyfriend. He is the bio-father of my youngest child. He is HIM.
But always-there was a relationship. It's just that the relationship shape is free to change whenever and however as life carries us along.
To me stability comes when you accept that changes will come and THAT IS OK. In fact, that is GOOD.
My best friend Mr. LR (no we aren't a couple and never have been); was gone from my life for 12 years due to personal priorities in his life. But when he reappeared; we are still best friends. Shrug. No questions asked in terms of "where were you". Just "hey! Nice to see ya!"
That sort of acceptance of change allows stability. Because there is no control and without control both people are free to be whatever it is that they need to be without fear. Which in turn allows you to keep bumping into each other and then like a kite-being loosed to fly to the far ends of the earth and then bump into each other again repeatedly-without fear or concern that anger or hostility will arise because you are being yourself.
(ok wow-I need to hush my mouth)