Spending many hours in the office; how do you deal with the loneliness?

I could ask it elsewhere, but HN users seem to better understand the problem I'm talking about. I go to office in the morning and leave at nights (sometimes past 12am). During the day, I have little interaction w/ other people and honestly, they seem not interested in having a conversation with others. I'm not in a relationship either. So basically after leaving the work (or even during the day) I get this crushing feeling of loneliness. My coworkers seem to be fine, however they leave much earlier. Am I doing something wrong? What would you do to not feel lonely?