Better hope he has a really secure job then, because just not simply having enough money that month to pay it all himself is a perfectly valid reason to ask his PARTNER for help.
Also, being his PARTNER is another perfectly valid reason for him to ask for help, even if you two agreed that he'd pay 100% of the rent when you two married.
Also, being his PARTNER is another perfectly valid reason for him to ask for help, even if you two agreed that he'd pay 100% of the rent when you two married.