What's wrong with doing a cheating prank?

I've done that in a couple past relationships and all the girls were still upset after telling them multiple times it's prank.

I never cheated on a girl ever. I just like doing pranks.
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+1 y
My joke is me pretending to have a serious face and delivering the bad news that I ''cheated''.
What's wrong with doing a cheating prank?
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