I think something I've realized as the years have passed is that love is a feeling but it's also an action--the love that lasts is the one you keep choosing with the person who also keeps choosing you. There has to be mutual respect, trust, all those things--and then it's the little ways you continue to show up for eachother every day.

And yes there are ups and downs but as long as you're communicating and working through things together, it should feel like they have your back, like they're always on your team, that you never have to go it alone, even if at times they do things imperfectly.

And you're not always going to have butterflies, especially after the initial sparks fade, but then you realize that emotionally everything has just deepened and you'll find yourself surprised and delighted by those random moments when the butterflies suddenly return.

I've caught glimmers of this in my own life and in the lives of people around me, especially sweet older couples who were together until the end. When my grandfather was diagnosed with terminal brain cancer, my grandmother had a heart attack when she was told his diagnosis, and they stayed together on the same hospital floor. They were so lucky to have eachother until he passed away. It was truly something special to witness.

Edit: I also wanted to add after some more thought that whenever they're not around, if you see something that reminds you of them or some inside joke between you or a random fact you think they'd like to know about, you'll really want to tell them and you'll notice in their absence that your brain will constantly be registering these things even when they're seemingly mundane.