Maddie 10 heart event

Hi. I'm already happily married with Maddie, currently I have maxed hearts (14). My problem is that I still haven't received the letter for the 10 heart event and I don't know how to trigger it. Already had the letter for the 8 heart event. It is spring right now. I need it to buy the weapon from the Ridgeside woods and to progress the story. Anyone can help me please?