“Holding hands is fine, but keep it at that. Even if it is your honeymoon, the complete strangers sitting around you will not want to watch you consummating your marriage at your seat.
“As for joining the Mile High Club in the aircraft bathrooms, most bathrooms are tiny and not very clean, is it really worth it?”
Other passengers won’t want to see couples being overly affectionate on their flight as it can be very offputting.
As the majority of planes seat passengers in three, it could make the third passenger very uncomfortable.