It may not be a consideration in court, but in my area there have been several instances of a child being killed by the bed buddy of the custodial parent. I believe the statistics are that a child is more likely to be injured by a non-parent adult in the home than by a parent. Any parent (CP or NCP) should be concerned about who is living in their child's home. With the current trend to llive together without the long term commitment of marriage, the no paramour clause in custody documents should be considered to determine if it is in the best interest of the child.
This situation is particularly troubling since one CP is looking to reduce the co-parent's time, and it is the bed buddy posting the question.