well i almost gave up on a pair i was breeding and this was on youtube but this is what i learned: condition the female, introduce, bubble nest and then let the male betta beat the heck outta the female and then they spawn. this is really weird. thats what my betta pair did.
Imo, if your female recieves any visual damage from the mating process, you didnt take the correct steps in fully conditioning the pair, or you misgauged the aggression of the individual fish. Either case, you should of took your time, and realized no matter how quickly you try to get your bettas to spawn, its a 4+Month ordeal of watching them grow, whats the rush? i never did get why breeders set up specific breeding methods to induce breeding quicker, its not like a whole 2 weeks earlier of a spawn will affect their growth that much. why not just take the extra step in conditioning them to make sure their ready for each other, instead of assuming, and having to remove one of the 2 because of aggression.
But i myself, am Barely a novice breeder at best, so what do i know? xD