Stable Mate Conundrum

I can be selfless.
I can be shallow.
I can be told when to throw in the towel.

You can be ruthless.
You can be sage.
You can be happy with me off the page.

We can be lovers.
We can be friends.
We can be tricked into making amends.

I can be selfish.
I can suck marrow.
I can remember when all hips were narrow.