I believe its loneliness that is over clouding your thinking , so when you see your g/f all that sadness and loneliness goes away .
You need to find something that you enjoy that takes your loneliness away .
Right now it's your new g/f but you need to find something else or your going to seem to needy and it might scare her away .

My advice is find a hobby that you enjoy and that loneliness will soon go away