Everything.
I never imagined a relationship could be this happy.
I'm not too bad health wise but I sometimes get a bad back or pull a muscle and am currently still feeling the effects of a bad sciatica attack where I was screaming in pain. It was months ago and my leg is still numb/painful and my toes feel like they're frozen. DH will give me a massage whenever I ask because he knows it takes the pain away for a while.
When we brought DC3 home from the hospital DH popped the Moses basket at his side of the bed. When I asked why as I was BFing, he said, "Well I can soothe him while you get yourself sat up and comfy, then I can pass him to you"
It's that sort of kindness and thoughtfulness he shows all the time.
In fact, as I type this, he's just walked in the bedroom with a coffee for me!
Our son is exactly like his daddy. Always thinking of others. If someone offers him a sweet, he takes three and gives one to each of his sisters. He always asks if there's anything we need. He jumps in front of fighting friends and says, "Whoa lads, don't fight. Let's sort this out!". He stands up for the picked on kids on the park. He'll find a lonely child and go sit with them.
So that's the best thing my partner has ever done. He gave me three children just as wonderful and kind as him.