Trust me you'll get caught. Women just know these things. Hell, I could see it now, you go home visiting your parents and your mom will figure it out, lol.
Anyway, I'd tend to go with what BJ and Heather are saying. Of course like I've said numerous times if you think your in a dead end relationship then I'd say go for it, of course first break it off with your girl.
I ain't an expert on long relationships though. I think my longest relationship was about a month. I'm holding out for the hottest women who I get along with and isn't all materialistic and s***.