The female is safe until she is unable to spawn with the persistent male. The male will then try to drive the female away to make room for a new female. The term "bond" that gets thrown around in the aquarium trade is misleading. The only bond that ever exists is when a male and female combine their efforts to secure a territory, spawn, and defend the fry for 3-4 weeks. After that time frame, the bond ceases to exist.
I think you see more mate killing in larger fish for several reasons. One, the male is larger and can do significantly more damage in a short period of time. Two, big fish have larger territories, and the female can not escape the males attention. Lastly, it is easier for smaller fish to move out of sight in a aquarium with some cover.
My .02