Is it ever ok

It depends on the type of person you are. I say yes to that because as a mother i always put my kids happiness before mine. There have been many occassions over the years ive refrained from doing something that woukd make me happy because the people i love would be unhappy by my actions.
So for me the answer is 100% yes.
But i know plenty of peeps that feel they have to put their own happiness first because they dont feel they would make anyone else happy of they werent happy themselves x

It is , but be careful. There are a lot of people that would take advantage of that !!!!

Sure, I think we do this unconsciously when we love a person.

Yes when in a relationship it happens without thought if it is a true love type relationship, because the other person should be doing the same for you!

This is absolutely what happens once you have a child!

Of course it is...that's the cornerstone of selflessness.
You just gotta be selective and smart about it.
It's not ok if someone else's happiness is going to result in a lifetime of misery for you.

Sometimes its a compromise that is acceptable
Every time its a punishment you put yourself through, becoming second to them.

only if they feed you cake while touching your knees, saying you lost weight

Yes, but you need to put your [i]needs[/i] before anyone else's needs. Otherwise you'll be frustrated.

I used to do that, but not anymore. My husband and I are pretty equal in our happiness.

Not if it doesn't make you happy to do so.

No, unless it's your child.