Whoa there turbo. Maybe the relationship isn't that strong if you can drop it just like that.
I wouldn't say flirting is cheating, but I read somewhere that there is such a thing called emotional cheating. Where a significant other puts all thier time and energy into another person. So when they get home to you they have nothing to talk about with you since they already have talked about it and put forth the energy with someone else.
What do I know, I think everything on the internet is true.
Flirting is more forgivable then cheating... don't place them on the same level.