- "As Mii relationships develop, some might become couples. And eventually, there could even be some weddings! One day... A married couple might even have a baby!"
- — Tutorial, Tomodachi Life
Love is a mechanic used in the Tomodachi series. It's similar to friendship, but deals with the romantic side of such, where someone has deep affection for someone. After a Mii becomes friends with opposite-gender Miis, there is a chance it will get feelings for up to two of them at a time. The Mii will want to confess their feelings to them (if there's more than one Mii who they have feelings for, they will ask the player which one to confess to.) and if it goes well, the Miis will become a couple.
Miis who have love-related problems will have the pink heart icon on their window. Upon entering the room, they will either appear worried and have pink, floating hearts hovering (containing a question mark) around them, or they will act as though it is any other problem. In the first scenario, the music will change to a variety of tracks depending on the issue upon entering their room.
Confession
A Mii confessing his love
Sometimes a heart icon will appear in a Mii's apartment window. This means a Mii has developed feelings toward a Mii of the opposite gender, or the Mii suspects another Mii has feelings for them.
When a Mii develops feelings for another Mii, they will want to confess their love to them. When the player decides to help out, they will pick how the Mii confesses, where they should tell them, and if they should get changed first. The options the player chooses here have no bearing on the outcome of the confession. After they confess, if the Mii's love interest agrees to go out with them, they will begin to date. However, if the love interest rejects them, the Mii will be upset and gain sadness. In some cases, hitting the thought bubble of the rejected Mii whilst they are upset may trigger the option to retry the confession. This time, the Mii will give the other Mii a gift, and the location of the confession will be random. If the second attempt fails, they will gain more sadness and give up entirely.
Occasionally, a Mii may wonder if a certain Mii likes them. The player can say whether they do or don't, or trigger a confession cutscene (by hitting "Go for it!"), similar to confessions. Unlike other love problems, they do not appear worried and the music does not change. If the player hits "Go for it!" and the Mii gets rejected, they will once again gain sadness. Unlike the above scenario, they will not try again if their thought bubble is tapped.
Two Miis can also become sweethearts if a mutual friend of the two Miis sets them up with each other on a date. If it ends with them wanting to hang out again, they automatically become sweethearts without confessing their love. If not, they remain friends and none of the parties involved gain sadness. If they "don't hit it off so great", one of them will wonder why would their friend want them to go out with the other Mii.
When a Mii confesses, there is a chance up to three other Miis may interrupt the confession and ask the love interest to date them instead. If the love interest picks the first confessor, they will automatically begin to date; if they choose one of the interrupters, they will ask the player if they like the idea of them dating. If the player agrees, the Miis will smile lovingly and begin to date; if the player disagrees, the Miis will be shocked and sometimes faint, and the date is off. There is also a chance the love interest will reject everyone. Only the first confessor gains sadness after either of the latter two occurs.
Proposal and Marriage
A Mii proposes to his sweetheart, who happily accepts
When the sweethearts remain in a good relationship long enough (often for as little as 24 hours), one of them will want to propose to the other and get married. If the player agrees to help out, they choose where the proposal takes place and decide whether they should change their outfit. Unlike the confession, the Mii is "really nervous at proposing at the right time" and requests the player to help them out by letting them know when the sweetheart is thinking of them.
The proposal takes place as a minigame. While the proposer is planning what to say, the sweetheart is shown to be easily distracted and will have a variety of thoughts going through their mind, represented as cycling pictures in a thought bubble. When the thought bubble shows the face of the Mii who's proposing, the player has to use the stylus to quickly touch the heart that says "NOW!", to signal the Mii that the sweetheart is thinking of them and to continue the conversation. The player has to do this four times, and they get three chances (represented by three hearts floating between the couple).
When the proposal ends in success, the Mii will give the player a gift, and the player gets to see their wedding, and then their honeymoon. After such, the "sweetheart" bar on their profile chart will change to "husband/wife", and they will settle in a new house at Mii Homes.
If the Miis are children, the gift the player receives will always be an Age-o-matic, and the player should use it on the couple before they can get married. If the player agrees, the Miis will become adults and carry on with the wedding; if the player refuses, the wedding will be postponed, but the player has to help the Mii propose again.
A married couple taking care of a baby
After a while of marriage, the married couple will think of having a baby (if the option is enabled). If the player agrees, they will give birth within 36 hours to two days. When their baby has been born, the player can choose their gender, appearance, name, and personality, or choose to leave it all to nature/the parents. The baby grows over the course of six days; during such, the player can babysit them. When the baby is fully grown, the player can choose to move it into the apartments or send it off as a traveler.
Breakup
A couple fails to work things out, resulting in a breakup
A couple is not guaranteed to have their love last forever. If their relationship drops to a low enough level and their love isn't working out, the player has to decide if they should move on, or try to work it out. If the player decides the couple should move on, this triggers a cutscene of them ending their relationship at the cafe. If the player wants them to work it out, they will get a cutscene of the Miis in the opposite's apartment with the lights out and a clock ticking. If they cannot work things out, the clock bongs and they will have to break up; but if they manage to do such, they will continue their relationship. After a breakup, both Miis will gain sadness; but there is a rare time where only the first Mii will gain sadness.
If two sweethearts break up, one can tap the opposite Mii's thought bubble and get a flashback of the wonderful times they had with their ex-lover.
If the Miis were married, their house in Mii Homes will vanish, and if either of them were kids and made into adults with the Age-o-matic, it will automatically wear off.
Rarely, after a breakup, one of the ex-lovers will miss their partner and want to get back together. If the player agrees, they will talk to the partner, and the scene plays out like a regular confession. If the ex-lover agrees to get back together, they will return to being sweethearts; if not, the first Mii will gain sadness. Sometimes, the ex-lover will immediately refuse, which puts the Mii in sadness.