people in relationships can be depressed, people with kids can be depressed, people with loads of money or their dream job can be depressed. depression is a disease and it does not care about your circumstances or relationships with others. some people have a genetic predisposition for it and others endure trauma that induces it. I've been in a relationship with my best friend for a year and a half, and I'm still dealing with chronic depression– it doesn't have anything to do with him. he is wonderful and treats me well and I love him with my whole being, but I am still depressed. for many people, a relationship doesn't fill an internal void unless not being in a relationship is specifically what they are depressed about.