I have a few tricks...
Recently I placed my two male bifas in a 100gal pond, I then put my syn/parrot female in a cage made out of plastic "eggcrate" light diffuser in the pond. She got to see her intended mate be the dominant male without being able to kick his butt as she had been doing previously. Last night I put them together in a 55 with a few texas fry for targets/dithers, she is dominant over him but does not chase or bite him anymore. They seem to be bonded, they chase other fish away together etc.
This works to get a male to accept a female too, let him see her kicking butt and taking names with the other girls...restrain him if you have to with a divider/cage etc, but make him watch her being the queen bee, cichlids will always choose the most powerful/dominant fish for a mate, no matter which sex they are. I've used this method with or without a cage/divider more than once.