Is it normal for one's happiness to revolve around making someone else happy?

For example, consider some women who downplay/sacrifice their needs and are incapable or unwilling to say/do what they want. I've known a lot of women like that. Currently, I met a girl this year and she prioritizes other people's happiness over her own, to the point that her happiness = making someone else happy. I don't think that is inherently abnormal, women are known to be innately nurturing and selfless. But I feel it's not normal when that choice is made on the basis of feelings of worthlessness, fear of being vulnerable, being insecure, having low self esteem etc.

Me being me, having a bit of a savior complex, I often insist that she states what she wants, at least sometimes... and that during our interactions, not everything needs to be about my preferences, schedule, needs etc. But lately I've been wondering... what's the boundary between trying to help someone and trying to change them. What do you think?