Once the matchmaker has come, connect with the tamagotchi it loves. You will first see each tamagotchi shaking their as if they're saying "no". Then one of the tamagotchis that is connected will move to the other one. Then on the other ones screen it'll show the tamgotchis facing each other with a heart in the middle. Then you should see fireworks, this means they are married. Then you'll have babies. You'll have to take care of both the adult and the baby. The adult will take care of the baby. You have to take care of the adult .
I noticed with my tamagotchis that Adults normally won't make a baby - even with their best friends - until both the boy and the girl have been adults for 24hrs.