Just read this post by a forum member on Bungie.net:
“Girls are better to play Halo with for the same reason that girls are better to do everything with.
Basically they smell better than guys, they’re softer, they’re nicer to look at and they have the affect of making you act like a better person when they’re around.
I can’t think of anything I enjoy doing that I don’t enjoy doing even more with a girl.”