if living together, both parties should share utility, grocery a

renting expenese since currently my other rooms rent out. if ever we decide to get married, he should not be on title and i pay mortage by myself. not sure how it works. now we are like partially living together. he spends the nights 4 days of a week in my house and I sepnd 1 night in his place. and we see each other 5-6 days a week.