For me the reason why I want to spend the rest of my life with someone is because I don’t want to be alone and I don’t want to be lonely. Once you reach a certain age, you will discover most of your friends have gotten married and started having children.
Your friends get wrapped up in their lives, have less free time, and it’s difficult to maintain friendships, even longstanding ones. I don’t want to have to constantly search for someone to do things with such as go shopping, go to movies, concerts, plays and museums, sporting events and a lot more.