It's normal that he is intensely interested in members of his own species, especially when you're not around that much. He probably hasn't developed tight bond with you yet. The more you do with your dog as partners, the closer the bond and interest in you he'll have. It doesn't mean you have to attend to him 24/7 but plenty of involvement really goes a long way. If your room mate does a lot with him, he may naturally tend to look to her as his caretaker. Spending time training (just short, frequent sessions) helps your puppy bond to you if you use positive reinforcment methods and build lots of trust.
I'd recommend a good puppy training class with a gentle, knowledgeable trainer who comes with recommendation. Watch a class first before you sign up. You'll learn ways to get him interested in what you're doing with him. He needs to learn to do the various skills in a distraction free environment first before he can possibly give you any attention where there are other dogs. It's a learning process that goes along with maturity too....which doesn't happen quickly. But there are neat little tricks to get him interested and have fun learning. And that's what is needed to have a happy, focused, well mannered dog.....FUN while learning.
You can browse the forums here, do a search (up on top) for things you're interested in. There are also good books....lots of threads here on books if you use the search option.
Have a look at this site. It's really, really good!
http://www.clickersolutions.com/articles/index.htm
