A sweetheart (known as special someone in the European version of Tomodachi Life and lover in Tomodachi Collection) is a term for Miis who become a boyfriend/girlfriend after a successful confession or set up. Various problems can cause sweethearts to break up.
Miis can become sweethearts in two ways: The first way is the love confession, where one Mii develops feelings for the other, so they confess their love to them and if they accept, they start to date; if not, the Mii will gain sadness.
The second way is a set up, where a friend of two random friends of theirs will set them up on a date, and if it ends with them wanting to hang out again soon, they will automatically start dating without confessing their love. Sometimes if the setup fails with them "not hitting it off so great", one of the Miis will wonder why would their friend set them up with the other Mii. This is exclusive to Tomodachi Life.
Miis may want to break up if they argue a lot or their relationship status is low. After a breakup, both people in the relationship may become depressed. If the relationship status remains very good for long enough, one of them may want to propose and get married.
- Sometimes the sweethearts can visit each other at either of their apartments and stare at each other lovingly, as hearts appear. If the player watches them like this long enough, they will notice the player surprised, then have a freak out for a moment before turning around and acting natural. Sometimes they go back to being romantic after this, or do another activity. If the player sees the sweethearts being romantic while sitting down/talking, they will not freak out.
- Oddly, even though sweethearts are in the game, they don't ever kiss or hug each other, possibly because of the target audience and would seem uncomfortable to younger players.
- In the English localization of the game, a child Mii cannot fall in love with an adult Mii. However, something like this can happen if two child Miis are dating and one of the Miis turns 18 (which would consider them an adult) before they get married. In that case, only the Mii that is still a child would have to be sprayed by the Age-o-matic before they get married.