Never expect the first spawn to go as planed. Even if you get a few fertile ones, Thats better than a lot of 1st time breeding pairs. Flowerhorns/hybrids are usually crazy overbearing in everything that they do, so being rational parents doesnt come easy for them.
Maybe if you see him trying to eat them again, shoe him away and put the eggs somewhere safe, with good waterflow over them to take the place of fanning. Either way your much closer to having fertile eggs now than you were 3 months ago. They will get the hang of it sooner or later.