According to my ex, who prides herself to be a social worker and a conflict solver, relationships are built solely on sex, not on interpersonal connections. But then again, she also thinks that you shouldn't ever apologize because it shows a lack of self-esteem, called the police on her best friend because she was jealous of her hooking up while she didn't and regularly posts "memes" about how terrible everyone else is on Facebook. Maybe she's just a nutcase.