(Sorry about the quality, and my finger sticking in the frame near the end to type on the keyboard :P).

Requirements:
Allen must be at blue heart or above. You also need to see his black and purple heart events before you can confess.

Once you get a blue heart with any bachelor(ette), depending on if you're playing as a boy or girl farmer, Hana will sell a ring that you use to confess to the person you want to date.

Give the ring to Allen on a sunny, non-festival Saturday or Sunday, between 8am and 11pm.

Note that if you saw a black or purple heart event on the same day, you cannot trigger a confession... even if the event was for a different bachelor(ette), I believe.

свернуть