The point of being a partnership, and then a family, surely, is that everyone's needs / success gets / happiness taken into account? And that the ideal is to maximise the 'total needs met / success / happiness' of the total group, not to consider each person's individually?
So in our family there are 4 of us - DH, DS, DD and me. At different points since our marriage, different needs have taken priority in order to maximise the success / happiness of the whole.
When DS was first born, and I was at home with him, we went abroad for DH to work - a career-enhancing opportunity he could not have taken had i still been working full time with no children.
We came back because DH's mum was ill - staying 'for a successful career' would have made DH massively unhappy.
When DS became a school-induced selective mute and we needed to move town to a different school, DH compromised his career progression to take a job in a suitable town.
I was a SAHM until DD started school, because both my DCs were somewhat 'unusual' when younger, and their happiness and success (and thus the total success and happiness of the family) was maximised by consistent care.
When I decided to retrain as a teacher, DH stopped doing the 'extra' at work that made the difference between 'driving for maximum progression' and 'doing fine where he was' to allow me to do so. He became a SAHD for a short time during my final placement.
Since then, I have worked P/T, full time and P/T again, always to do with 'success / happiness' of the whole family - whether that is allowing the DCs to be successful in specific extracurricular activities or in their schoolwork, or getting a better balance between what DH and I contribute to 'keeping the family ticking over', or enabling DH or I to maximise our career progression at critical points.
But the point is that it is always a decision based on the 'overall good of the family unit' (and sometimes wider family members), not an individual accounting.