A romantic relationship between two individuals with the intention of sexual gratification/procreation. The closest human equivalent is 'to be in love'.

A person in a matespritship may be referred to as 'matesprit'.

Also known as the flushed quadrant of the Alternians' relationship quadrants (MS Paint Adventures by Andrew Hussie).
Mom and Dad are in a matespritship.

Mom is Dad's matesprit. Dad is Mom's matesprit.

Mom is flushed for Dad. Dad is flushed for Mom.
by Rem (a Homestucker) November 2, 2013
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