I dont think i could ever involve another girl. I would end up either fighting or crying and fighting. . One time a few years ago kaneda and I weren't talking and he didn't know I was working in the movie theater and he brought his g/f there and at the time I had never felt so sick in my life. I couldn't breath it hurt so bad.
It can't, unless you're having a 3some. If your girl is down for it, then there shouldn't be any problems. Just pay more attention to your woman then the other girl.