There has to be a healthy balance.

First of all both people have to regard other person highly. Otherwise it becomes one sided when you please them and the other person just takes. It has to be give and take.

Second of all while you value other person highly you shouldn't forget your own needs and your importance. Putting other person first all the time and not value your own needs isn't going to create healthy relationship.

And it depends on what makes other person happy and if it matches my own values. If my partner (hypothetically) wants to smoke dope because it makes him happy (again pure theory) then no matter how much I love him it just ain't happening. Or if it makes him happy laying on a couch while house needs to be cleaned then it's not happening either.

I think the most important thing in choosing a partner is finding right match. I think most marriages fail because people choose wrong match and then try to work with what they have. Choose someone with same values abd life style and things in common and then it's more likely to work in the long run