What level of relationship are you with Cove in at Step 3? Because my character was at the Love stage, already confessed their feelings, and everything happened the exact same, with the added DLC content, then after the final beach gathering with the family and friends, they went to bed, Cove asked them to come out for the final time, to the back of the hill, they talked and reminisced, then the options popped up.
I don't know.
I think the trigger also has to do with when Cove brings up whether or not your character is willing to get married in the earlier Moments, when they're going out to jet skii.
If you say not right now, or something, maybe that makes it so the marriage options don't appear?