It is tempting to think of these as the same gift, just early. They are not. A wedding song lives inside a ceremony or a reception, surrounded by a venue, a dress, a guest list, and a first dance. An engagement song lives in the messy, joyful, slightly disbelieving weeks right after the yes, when the couple is still telling the story to everyone who asks and the ring is still catching them by surprise in the mirror.
That means the writing is different. Engagement songs can be looser, more inside-joke heavy, more about the specific proposal than the general forever. They do not have to work for two hundred guests. They have to work for the couple, their parents, and the handful of people who already know the real story. Lean into that freedom instead of writing a wedding song six months early.