Below find a list of how to trigger the heart events:

2 Hearts
Enter the Town Map after 10 pm
Must not be raining
It is recommended that you talk to Dwarf after this event.

3 Hearts
Must have seen the Seal of Promise event.
Dwarf and Krobus must both be at 3 hearts
ONLY triggers on Spirit's Eve
Will trigger immediately after you exit the festival
If using Grandpa's Farm or one set to "ActivateAltSpiritsEvent" you will receive a prompt to return to town.
(Please do return to town, if you do not you cannot see the event for another year).
If you are NOT using Grandpa's Farm or have 'ActivateAltSpiritsEvent' false, it will take you immediately into the event.
This was to avoid an issue with actor positions from modded farm maps.

4 Hearts
Must have seen the "Seal of Promise" event.
Enter the Mine before 11am.

5 Hearts
Must have seen the "Seal of Promise" event.
Enter the Mountain map on a rainy day after 12.30am
Must have 4 hearts with Krobus
Must NOT be a Sunday
This event will end the day. If you do not wish to end the day, hit 'skip' on the last message box. (There is a prompt).

6 Hearts
Krobus and Dwarf both at 6 hearts.
Must have seen the 4 and 3 heart events
Must not be a Sunday
Visit Krobus in the Sewers

7 Hearts
You will receive a letter with a request

8 Hearts event one
You must have fulfilled the above request
Visit the Mine.

After seeing that one:
You will receive a letter with an invitation
Visit the Forest after 11pm
Must be raining and must not be a Sunday

8 Hearts event 2
Must have reached the Caldera
Enter the mountain map after 9 pm

This triggers two other events:
Enter the Beach after 6pm.

Enter the Caldera after seeing the above event

9 Hearts
Have seen 8 Hearts event one
Visit the Mine.

10 Hearts
Krobus  and Dwarf both at 10 hearts
Must have seen the above event
Visit the Town on a rainy day after 9 pm

14 Hearts
Enter the farmhouse between 7am and 4pm.
Must have Farmhouse completed.

After seeing this event:
Enter the Railroad after 10

***

TO ROOM-MATE DWARF (ie learn the recipe)

• You must have Dwarf at 10 hearts.
• If Jasper is installed, you must have seen his 14 heart event, either through marrying him and having Free Love - or through his platonic 14 heart (enable this on in his config).
• If Jasper is not installed, Gunther will offer you the recipe.
• (Note that the process is quicker without Jasper, but more immersive with him, how you choose to play is up to you!)