Davy, have you seen the male eating the eggs? Or do you presume only the cause being the eating male? Mind, that it sometimes looks like eating, whereas it is only caring for the clutch.
Anyway, the clutch disappears again and again. I should recommend to you to take either the adult fish out or the cave with the eggs. The latter would make it necessary to put it in an extra vessel with exactly the same water (!) and to use funghicides and additionally pick out bad eggs every day several times. The better method is to take the adult fish out, Here, again it could become necessary for you to replace the caring father by own activities.
But the most important aim is to bring at least some eggs to development. Possibly, you have to look in the latest census who still has some P. phoenicurus besides yourself and try to get some additional individuals for exchanging them.