Responses
It's just rumors, though? The nobles may have started a running joke about it since he's unwed at his age, 'cause obvi there MUST be something wrong with a gorgeous unwed man.
It would be the same if a couple were married for 2-3 years w/o having at least 1 kid. Rumors of infertility and the like would pop up.
I imagine the pedophilia thing was someone's attempt to slander Mars.

So we really going to ignore the pedophilia rumors but then shame the 13 year old princess who married the grown man. Okay. Makes complete sense