It sometimes takes young angel pairs a few tries to get it right. They sometimes eat eggs/fry/wrigglers the first few times. I always let my angel pairs figure it out. The most stubborn pair I ever had, a koi pair, probably ate their fry a dozen times before finally "getting it" and raising the fry. I'd be patient if they're a young pair and let them try to work it out. I'd suggest a larger tank (20 gallons or 29 gallons) with a few peaceful dithers like large tetras.
If you are impatient, you can wait until the eggs hatch and then siphon the wrigglers into another tank. I've done this multiple times. I set up a 20 gallon with the same temperature as the parents' tank and put a net breeder in it. The net breeder keeps the wrigglers off the bottom where they'd likely fungus and die. Once in the net breeder I position an airstone about 1/2" away to keep water circulating over them.
The fry should go free-swimming in 5 - 7 days and then you should begin feeding them as soon as they're all up and about. I use BBS but you may be able to try some decapsulated brine eggs or Hikari First Bites if you don't want to hatch live food.