When my male electric blue recently started showing interest in the female on the other side of the divider. when he had his back turned his mating partner snipped him and now he's dead. He partially coated the eggs him and his partner laid two days ago. After i took him out she eat the good eggs then spit the bad one's on the other side of the divider. Now i'm a firm believer of fish having relationship rage. Might be that! Lmao
Also if you watch the interaction between fish. Sometimes one might be too controlling. Most likely the female, because the male is straying off. That's a bad sign and she might just eat the eggs.