Of course you can also love someone if they treat you badly or make you feel sad. And you can experience very different kinds of love – for your parents, your family, your friends, or for a pet, as well as for a partner.
There's no one-size-fits-all formula in relationships, and what works for one couple might not work for another.
Usually a relationship starts when two people fall in love. They may begin seeing each other on dates. In some cultures a couple can live together and have a sexual relationship without being married. In others, couples get married before they live together or have a family.
Unfortunately, not all relationships last forever. There are all sorts of reasons why relationships end, and breaking up can be a painful process.