This questions in my opinion can be addressed in two ways.
Firstly, the tendency to cheat as in having the flirty tendency and probably carrying out soft flirt here and there but you call it being caring and friendly.
Flirty people are cheaters or potential cheaters as flirting is a means to an end. Most people flirt because experience tells them to and it will give them confirmation (whether the flirtee is interested in them or not). While others flirter are in the category of novice flirter, they are new to the flirting thingy and are just experimenting or finding out what works for them. (If the end game is to get the flirtee to your bed, you are surely a cheat)
Secondly, the people in this category are virtually everyone that is old enough to grasp the concept and has entertained the flirt thought one way or the other. Entertaining the thought is not the problem but acting on it. What you tell yourself when the thought comes is extremely important as it has the power to change you and your perception about flirting and cheating, if you keep disapproving the though overtime you will be fine and you will always know where to draw the line.
I don't think anybody say you're supposed to become blind to the beauty of people once you're married. Recognizing another person as interesting, funny, beautiful, is not a "tendency to cheat", that's just appreciation.
Cheating is a tendency to cheat.
Interestingly similar to a question I just answered.
Attraction is a naturally occurring, biochemical response that we all experience.
It is natural to feel attracted to others who are not your mate, but acting on these primal instinctual impulses or not acting on them, is what defines what kind of person you are. The first of these two, is a cheater.