Can someone tell me why my parents act this way?

Recently I broke up with my ex. We were going out for about three years when it all ended. I was feeling very depressed. I started going out with friends more often then before because I now had the time. Last week I did something I feel kind of bad for. I disappeared for about 5 days. I went and stayed with a friend because I wanted to think. I wanted to get my mind in order to think of the things I needed to, At home I get no privacy, so I never get a chance to just think. I knew my parents were going to be mad but I was willing to take my punishment. When I got back though, I got something completely unexpected. My parents were just happy that I was home. I felt like **** for doing it. My dad seems to sympathize with me the most. I think he knows how it feels to have your first love lost. My mom just talked to me. I was really caught off guard. I don't feel like I deserve to be treated nicely for what I did. I feel bad but don't know what to do about it. I've been writing a lot (I want to become an author) and they've been supporting me. I told them that next year I can still get into university even though I missed a lot of school. I'm happy that they support me so much, but I feel like I don't deserve it. I don't know how to feel. Please, mothers and fathers and anyone who can help, tell me why my parents are acting so nice to me when I've been so stupid?