The fastest way to get it is to send gifts, but this costs money, and you cannot send things across channels. But there are also ways to do it without spending any money, and you can have exciting and worthwhile activities in the Marriage Tree.
After players complete tasks, their heart rate will also increase a lot. Playing games together, dancing together, and escorting Huahua can also quickly increase their heart rate. Although marriage in the game does not require intimacy, there are still certain requirements for heart rate.
After everyone plays together, the excitement level will increase, but this method is still very slow. The fastest way is to send gifts, but Android and iOS cannot be interoperable. Although they can play games together, the gifts cannot be interoperable.