Tamagotchi On App - How to marry your friends?

My friend recently bought a Tamagotchi, who lives across the country from me, and we wanted to marry our Tamagotchis together through the app when the time came. How do we do that? Also, is my Tamagotchi only present on  my profile when I'm connected to it? There's a little Tamagotchi device with a ? mark on it when I'm not connected. My friend and I have already added each other, so how do we marry our Tamagotchis that are adults?

it takes some trial and error, but usually as long as you're in the plaza with your friend at the same time, you should be able to find their tamagotchi

sometimes it's a little harder if there's a lot of people in the plaza at once, so if you can't find them, try going into the arcade and back out to refresh which ones show up, and just keep trying until you see them

you can also try going into the Tama Party at the same time, but i haven't tested that myself so i'm not sure how reliable it is