I don't this trend is gender-related.
I think this boils down to who gets more lonely.
So in LDR cases, rather than having a specific gender going astray.
The popular case is, the one who leaves ends up with more temptations to go astray.
Imagine, the one who leaves goes to a place full of strangers and would usually have the resources to pleasure oneself.
And it really is pleasurable to be spending your time with a warm human being.