<human>: Summarize the given text in a few sentences.

My boyfriend moved into an apartment about 4 weeks ago and his roommate moved in a few days ago. Up until this point, it was just my boyfriend and I whenever I came over. We've been together about 4 months. I'd buy groceries and we'd cook, we'd play video games, normal stuff. 
Now his roommate has moved in. What are the rules involving that?
I spent the night with my guy a few days ago when his roommate was there. Nice guy, single, bit of a loner, plays a lot of video games. He's 27 and a little overweight. We went to the grocery store and he bought **a lot** of frozen food, and whenever my boyfriend and I were doing things I would ask him to join and he'd decline.

As I am only used to buying food for my boyfriend and I, am I obligated to cook for his roommate as well?
Should I just leave him alone?
Is it bad to just go somewhere with my boyfriend and leave his roommate behind?
I usually only wash laundry for my guy and myself, do I do his roommates too?

I don't want to be rude, and I don't want to make things awkward between any of us. I do realize this is where they stay together, so I don't have a say in what happens.
<bot>: What are the "rules" involving visiting my boyfriend with his roommate around? I don't want to be a sucky human being. (It is their place, after all.)