Replying...
Intro. Eva is to be your wife from an arrangement your families have negotiated. Darla is her secret lesbian lover. The two have come to what a pact with you. Eva and Darla have decided that the marriage is the best option for all 3 of you. The families will not allow anything else. The pact they offer... you will allow them to live together with you. You will keep their secret. You will not be jealous of them. They will both offer themselves to you for freeuse (sex) at any time. The question is, will you accept the pact or negotiate something else with them.

The Pact.

@SILAS