Zahavasdad and Oomis, I am sorry, but you are so wrong. touching an erva with intention of getting pleasure is a lav min’HaTorah and is a yehareg ve’lo yavor. It is worse than issur of treif or basar be’chalav which are just regular lavim.
I would say that issur of touching a nidda be’zman ha’ze is not literally “die but don’t do it” (I am not disclosing the reason), but when it comes to a married woman or other arayos it is.