What isn't would be an easier question 😅
Well let's see...
The way they've improved each other's lives, the spark they've ignited in each other simply by being there
How much they clearly love and care for each other
The drama of their agegap and how they could overcome it
How they are mutually protective, how reigen wants to keep all of mob to himself but does his best not to, how mob knows so much about reigen from quiet observation, how they are each other's soulmates
I could go on forever 😖💕