You're not the only one without someone to love. Many, many people don't have a partner regardless of how badly they want one. It's perfectly normal to long for a partner, almost everyone goes through it at one point or another. Loneliness can hurt, a lot, but there is value in learning how to be happy even if you're alone. Love will never solve all of your problems - no matter how much it may feel that way - and it also comes with many problems of its own that you will need to be prepared to deal with.
Your existence should not be defined by whether or not you have a boyfriend or girlfriend. Relationships are only a small part of the many things that can make life enjoyable. Friends, family, hobbies, learning, traveling, doing things you've never done before. Not all of it can be experienced immediately when you want it to happen, but things will never stay the same forever. Change is always inevitable. Be patient and make yourself available to meet new people and try new things. When you're feeling lonely, go out and do something or hang out with friends instead of letting yourself drown in sadness. You may start to feel much better afterward.