If I have a bridesmaid does he need groomsmen?

My fiance does not have a close male friend or sibling to ask as a best man. At first I was relieved to not have to pick between my friends (I've been a bridesmaid in 4 weddings) but now I'm regretting having NO wedding party. I don't want him to feel bad- he moves around so much, it's hard to make lasting guy relationships. He has friends though-- how close do they have to be to ask to do best man? Any ideas for creative ways around this? I've considered just asking my best friend to attend but will that draw attention to the fact that he has no one? :(