Could it be?

You lied to me,
but I didn't care.

You cheated on me,
I showed no tears.

You called me names,
and I just did the same.

You caused me great pain,
but I didn't care for you any less.

You told me you didn't love me,
I just smiled and said OK!

Could it be, none of this bothered me; because I never loved you either?