Not only just you, muslims cannot criticise the Prophet or Islam, otherwise you will lose you entitlem,ent of virgin(s) in heaven.
Any religion that promises virgin in Heaven is a CULT.
In short,
You find 75 year old man having 45 year girl friend not ok, but a 54 year old Prophet having sEX with a primary 3 kid is OK. When I speak to muslims, I have to lower the moral standard BAR. You can criticise an infidel or other bibilical Prophets but not the sole Prophet of Islam.