We generally expect there to be love in marriages; certainly in romantic relationships. In some other kinds of relationships—friends, relatives—we also expect there to be love. Without love, it seems to me, a marriage is a business arrangement.
There are plenty of marriages without love. Some start that way (arranged marriages) and some just evolve into loveless marriages. I think that people could stay in a loveless marriage for several reasons, but I think the biggest reason would be security. It’s scary to have to go out and figure out how to live on your own again.
There are reasons to enter into loveless marriages, such as money or security or a safe place to bring up one’s children.
I have chosen a marriage that seemed to me to be more of a business relationship than a love relationship. I did it for the kids mostly, and partly for security. I think I also did it because I had made a commitment, and I loved my wife (even if I didn’t feel like she loved me), and I had hope that the love could come back, which it has, although that’s a work in progress.