I think my problem was with the phrase STAY AWAY. This, to me, means he's not even allowed to talk to her, which I think is ridiculous.

There is a line between appropriate and innappropriate behavior when one is involved in a relationship. Holding hands is a definite no-no. Flirting? Maybe- depending on what's said. Of course it would be crushing to have someone cross that line behind your back, but can you even imagine what it would be like to trust someone not to?