<human>: Could you distill the essence of the text into 1-3 sentences?

I recently moved for my new job, and I'm still trying to get established (find a dentist, all that jazz) and find new activities in the area (social, sports, etc.). I work in a small department with a nice but very distant group that are all international hires except for myself and my coworker "Bill." Bill is very friendly and is serving as a sort of mentor for me, and we get along well. He is pretty much my only "friend" (we're not that close) in the city and he is involved in several activities I want to join (mainly a basketball group). 

The only thing is that Bill is a single guy and I really don't want to come across as pursuing him (I am in a great relationship, and even if I wasn't, Bill's picture is in the dictionary under "not my type"). He is a friendly/jokey guy and I can't tell if how he treats me is normal, but I want to head anything like that off. He has met my boyfriend and I try to mentioned him occasionally, but we talk mostly about work. What are some tips for trying to get to know him/get involved in his groups while making it clear I'm not interested? I currently feel uncomfortable asking for his number/asking about his groups, but I also really want to get out of the house and have fun stuff to do (and I'm having trouble finding it on my own--it's a pretty antisocial area).
<bot>: Want to get involved in social activities with my new coworker but concerned that asking for a single guy's number so we can hang out on the weekend *really* sounds like flirting.