Earlier quoted context omitted.
Hate is irrational, and yet it does not justify murder. Similarly, you can love w/o sabotaging the relationship by marrying, giving the other party a red button and a strong incentive to press it, effectively pushing the relationship out of balance. Statistically, they will. And statistically, you'll be screwed.
Is the incentive financial? Isn't this assuming you earn more?
No assuming. Refer to data on Divorce Court rulings on who gets screwed.
Spoiler: It is men, as well as the children if any.
Hard data shows what the odds are like for children who grow up in broken families.