OP, get to class early and get a spot in front. You'll have the most space in the front row, and the front row is often has the most coordinated people that know each step by heart...so they're unlikely to run into you.
If it remains a problem, I'd tell the instructor. I make everybody extend their arms to establish enough personal space for everyone before we start moving. Or I'll move everyone up a few feet if the back rows start to get too crowded.
I have a few men in each of my classes. Some are gay, some come with their wives and some are straight, single and just like Latin dancing. The creator of Zumba is a man, and he's quite the ladies man. Wyclef and Pitbul also like to Zumba.
http://www.youtube.com/watch?v=iRbZpHHid54&feature=share