"Through thick and thin".
My wife has been with me in my lows and highs. I don't understand people who think they are above or beneath anybody else because "success" comes and goes. I admit that when my son was born, my ambition for career advancement also dropped a little because I wanted to spend more time with him.
Relationships should not be a competition, and your partner shouldn't feel like he or she has to keep up with you.
If anyone ever leaves you because "you are no longer good enough for them," you should be relieved that you're out of a toxic competition rather than a healthy relationship.