The opaline male and the gold female are both colour morphs of the three spot gourami, Trichogaster trichopterus, and can breed because they are the same species.
The pearl gourami is a different species, Trichogaster leeri, and can't breed with the opaline male.
If you want to breed the opaline and gold I would remove all the other fish or move the two gouramis to a separate tank, as eggs and/or fry won't last long with other fish around. You'd have to remove the female after they've spawned as well as the male will turn quite nasty defending his bubble nest and eggs.