- "We've decided to get married."
- — Mii, Tomodachi Collection
Marriages occur after a certain amount of time has passed and both Miis maintain a good relationship with each other. One of the two dating Miis will have a problem icon and say that they want to get married to their sweetheart. In Tomodachi Collection the marriage will occur automatically off-screen while one of the Miis gives a photo album of the two after successfully marrying. After the slideshow, the two Miis go on their honeymoon.
In Tomodachi Life the Mii will want to propose and there will be a mini-game for the player to help the Mii out. The player can choose whether or not to accept their request.
In the Mii's apartment the player will hear intense violin music in the background, accompanied by a slow heartbeat. Upon tapping the Mii's thought bubble, the Mii will tell the player they want to propose, and the player can choose to help out. Unlike confessions, the player cannot tell the Mii to wait, and has to help them out immediately.
When the player agrees, the Mii will first ask where to propose to the sweetheart, which can be at either at a fireworks show, the train station, the amusement park, or a fancy restaurant. Then the Mii will ask if they should change clothes. Finally, the Mii will say they're really nervous at proposing at the right moment and request that the player should help them propose to the sweetheart by telling them when their sweetheart is thinking about him or her. After the player agrees, the Mii says it's time and they're going to propose.
- "My [darling/love]... will you marry me?"
- — Mii, Tomodachi Life
The Mii and the sweetheart will settle in the player's chosen location. This transitions into a mini-game where the player must help the Mii propose at the right time by signalling that the sweetheart is thinking of them. The game lasts four rounds, and the player has three chances to propose, represented by three small hearts floating between the couple.
As a slow heartbeat is heard, a thought bubble will rapidly appear and disappear over the sweetheart as various pictures cycle through, showing the various thoughts going through the Mii's mind. When the proposer's face appears in the sweetheart's thought bubble, the player must quickly tap on the "NOW!" heart button to let the proposer know that it's time to talk. When the player succeeds, they will give a thumbs up and the hearts will expand. The conversation differs depending on the round.
If the player miss, the sweetheart may abruptly change the conversation accordingly to what is in the thought bubble or, if there's nothing in the thought bubble or there's no thought bubble at all, the environment may disturb the conversation in several ways (such as passing train, crow flying by and cawing loudly, loud cheering, or a waiter/waitress suddenly checking up).
Upon failure, one heart will break. If the player loses all three hearts, the sweetheart will either ask to leave or fall asleep and the proposal will fail. Failure in proposal will cause the relationship to go down by one or two levels, or in extremely rare cases, a breakup. However, the Mii will not gain sadness. The Mii can ask to try again in the future.
When the player succeeds three times and the hearts are full-grown, the heartbeat in the background speeds up, and the player must tap the heart icon at the right moment one more time to finish proposing. If done so, the Mii will propose to the sweetheart, and the sweetheart will happily accept. Then, as celebratory romantic music plays, the Mii who had proposed will cheer while any other Miis around will applaud. The player can applaud by tapping the touch screen.
- "We're so excited for our wedding!"
- — Mii, Tomodachi Life
The Mii and their sweetheart will give the player a gift and proceed to get married. If the couple are kids, the gift will always be an Age-o-matic, and the player will be asked to use it on the couple before the marriage can take place. The player can choose to age them up, but if their request is denied the wedding will be called off.
After the engaged Mii couple gives the player a present, the wedding scene is shown. A bell is shown ringing as white birds fly past, and the camera shows the newlyweds; the groom wearing a tuxedo, the bride wearing a wedding dress and holding a bouquet of flowers, as a cake stands between them. They walk up to each other then face forward happily as we hear applause. Their guests are then shown, who are randomly chosen friends, parents or siblings. The men wear suits while the women wear either frilly dresses, loose-fitted dresses, bubble dresses, evening gowns, or gothic dresses. Then, in an overhead view, the bride tosses her bouquet over her shoulder as the view becomes a gold-tinted photograph.
After the marriage, they will spend their honeymoon in a random country, bring back a souvenir, and settle in a newly constructed house. The married Miis can switch between living in their house or in their own apartments.
A total of four locations can be chosen, each with different interactions:
|Fireworks show||The Miis will sit and watch the fireworks.|
|Train station||The Miis will wait at the station, as other Miis wait with them.|
|Amusement park||The Miis will ride the ferris wheel.|
|Fancy restaurant||The Miis will eat their dinner at the restaurant, as other Mii couples eat with them. Sappy music plays in the background.|
- When the proposal between two Miis is successful and they are kids, they get changed into their clothes for the wedding after they are turned into adults. However if the proposal is between two adult Miis, they do not get changed.
- Due to the presence of a wedding cake between the married couple, it's obvious the setting is at the reception and not the ceremony.
- It is possible to remarry a different Mii as well as an ex-sweetheart/spouse.
- If a Kid-o-matic was used on a Mii and they get married, then either that Mii won't return to its original height, only growing at the same rate as the opposite Mii, or they won't grow at all.
- If a child has an Age-o-matic used on them and gets divorced, they will revert back to a child with the text "The Age-o-matic wore off."
- The restaurant proposal is the only place that doesn't begin with a prologue conversation.
- at the restaurant proposal, the person that they are going to propose to will always be eating salad.
- At the fireworks show and train station, the Mii gets down on one knee and gestures with one hand out when proposing; at the amusement park and fancy restaurant, it does not do this.
- If the player uses their camera to take a snapshot, this will temporary freeze the action so they have a few more seconds to tap the heart if they see the proposing Mii's face in the thought bubble. This helps make proposing easier, in case they have only one chance left. Goes the same for using the HOME button.
- Since the restaurant proposal doesn't have the sweethearts staring into the distance, in the last round they stop eating their meals and there is no sleeping failure possible.
- If the proposal fails and the Mii wants to try again, it doesn't mean the same Mii will want to propose this time around.