Just copy pasting my last comment about it-
This one is a bit tricky, since you'll need to do quite a lot - it took me more than a month in game to get it because I was kinda lost too.
Make sure you only has one heart with him, 'k? It won't happen if you have the third heart (involving the Den event). But you'll need at least 40 likes too. I did with 70 and went smoothly.
First, you'll need to talk to him and help him with his job.
You'll need to progress on the Living Aspects of the village too, with Bernard.
Then the "new road" event, offering Ste to go to Bareshade and talking about constructing a new road since the underground can be dangerous. You'll also need to supervise and help the workers. (I got anxious trying to keep everyone alive, seriously).
I also went to the fair with him, but be careful on what you talk about. He won the guessing game (boy just loves our smell, and he knows we knows it) and gave us a Lucky Charm necklace. Wear it.
Then stay at your home in Bareshade, not the hut. At night he'll make a visit. Create a save file if you want to have the angry sex scene, but came back and choose to stop him if you want the heart. In the morning, grab his hand.
Hope it helps ♡