I know we still love eachother dearly! but why is my girlfriend afraid to commit?

I've been in a 9 month relationship with a girl. She is 18, I am 21. Recently we seemed bored of the relationship which led to pointless bickering. We spent A LOT of time together; she even lost touch with most of her friends. Now she tells me she wants a break. Initially I was upset but I realized that the relationship we built had gone in a terrible direction. We both missed the earlier days when we were spontaneous and enjoyed eachother much more. In light of this I asked her on a date. It was the most fun we had together in ages! but she stood firm on slowing down and physical affection was not appreciated. We planned another date in the future. BUT The next day she shows up at my apartment! She says shes lonely. We ended up spending time here doing exactly the same things we didnt like about our old relationship, only this didnt bother her a bit. I got upset and told her I can't do this. It seems like she likes the boyfriend companionship only without the boyfriend.