It's a bit 'grey' but... I think it's cheating. I got a tougher question. Is fucking a pussy in a can considered cheating? I'm very divided on this one... hard call.
I guess it depends on your significant other. Are they ok with it? Do they even know? but that all depends Short answer=yes its cheating
Seriously? Cheating is whatever you wouldn't let your partner do with another person. If you're okay with your girl giving blow jobs to other people, then I guess not.