Aside from being a good caring partner. Be the best version of yourself and therefore being irreplaceable.
Women can’t/struggle to downgrade.
So if a guy everyday keeps his physique looking really fit, works really hard, gets status and earns a ton of money to the point he can afford all the luxuries.
He’s going to keep the girl. As how can she get better when 99%+ of men are not like this.
Women look for the ‘best’ mate