You each give because you want to make the relationship better, not because you expect to get something back.

Your pay, your hope, only for our growth.

When I think about it carefully, I'm actually not giving up much

Ultimately, you and your career will pay the price.

It is harder to explain how lovers can feel that they can never get enough of their beloveds, since the beloveds have so much to give and might be giving their all.