From inter- +‎ parental.

interparental (not comparable)

1. Between parents.
   • 2015 August 13, “Developmental Trajectories of Social Skills during Early Childhood and Links to Parenting Practices in a Japanese Sample”, in PLOS ONE‎^[1], →DOI:

     For instance, laxness, poor supervision, inconsistent discipline, and interparental conflict are negatively associated with child social skills development.