When Wes Blew In
Wesley would never tell his fellow cadets what he saw when he arrived at his mother's new quarters on the Enterprise. Some views are way too scarring for the minds of children.
Sons should never come across their mothers engaged in amorous activity with the man they consider the only father they had. He'd heard about the change, and the raging hormones that had resulted in his new step-father and half-sister on the way.
Hearing about it, however is not enough preparation for walking in on your mother, naked, legs in the air, being pounded into ecstasy by the Captain.