For me, companionship would be my major reason.
someone to enjoy meals with, lavish in compliments, traveling, enjoy hobbies together and apart. which brings me to another aspect of marriage.
will you "allow' your better half to keep his hobbies he had when he was single? even if it means that he will be away from home for the evening hours? Your together time in the evening. will you feel abandoned by him/her? all alone again. So what will you do then? get your computer out to look for something entertaining? go out with friends to get home at about the same time as he/she does? cook up meals for the week?
Have you given any thought to what it will be like when you marry another person who has his/ her interests other than your love relationship?
I have several female and male friends who have chosen to remain single up into their late 60's. They all say they will never marry. what are your feelings toward this? They say they don't want anything else to worry about. They have enough troubles to deal with on a day to day basis.