Why must you be unfaithful

Why must you be unfaithful?
For women
Men, you shouldn't listen to your selfish heart
It doesn't really have a brain

Besides keepin' you alive, its existence is in vain
And how could I be so mean, and say your heart has no place?
Because mortal men fall in love again
As fast as they change their fate

I may be cruel, but think awhile about the hearts that you have broken, and match that with the empty vows and broken promises that you have spoken.
Now I'm not saying females are perfect
'Cause we all know its not true

But why must you be unfaithful
If her heart is true to you??