If your Tamagotchi turns into a teenager at age 3, then it will get married at age 6. If it turns into a teen at age 4, then it will marry at 7 years old.
the matchmaker comes 72 hours after yur pet becomes an adult at 10am, 3pm, and 7pm. she'll continue to come for a few days until you've found a partner or if you said no.