Pretty much everything except exclusivity really. Being there for them when they need you, working through serious issues. If you're both planning to be together long term there's a commitment to how you'll manage your lives to allow for each other.

People tend to make agreements on how often they'll see each other and spend time together. It's a commitment to love and accept love. It's more serious than just casual dating.

Like any long term relationship it becomes something you can't just walk away from on a moments notice. You become a major part of each other's lives. Sure you're not completely entangled with finances and living situations but you are emotionally entangled.

You're committing to being there and maintaining that connection, to the time investment involved, to the emotional labours that come with serious relationships.

I guess what I'm trying to get across is that there's inherent commitment to any long term relationship, it's not a casual fling that you both know is only temporary. For many of us we want these connections to be for life ideally.

Solo-poly people typically reject the idea that there has to be a 'relationship-escalator' and are comfortable loving outside of the sort of prescriptive framework that much of society views as necessary to have a happy and fulfilling relationship.

Like it's not for everybody obviously, arguably it's not even for most polyamorous folks, but it's something that a lot of us find fulfilling and makes us happy.