Honestly I would contend that marriage as a whole is utterly pointless at this stage and should wholly be removed.
With how much Onyx apples have been handed out through past events, it does feel unnecessary to get married at this point. The one chase item for the party quest has become a bit too common as an event reward.
Just wanted to let you know that the issue where characters being swapped inside Hero Squad causes the Client crash is known and is being looked into. A workaround for the time being is to stop attacking for 5-10 seconds, then swapping characters.