I pick up a female villager(50+ yrs old) and constantly make her kiss another male villager** until she gains her Master Parent status. I juts make sure I keep hearing the kissing sound when I do that. It doesn't take me 5 minutes! (Honest!!) You can try that method too if you like.

** My Male Villager is usually above 66 years old, so that he doesn't run away!! LOL...!!