After a certain amount of days you stop getting furniture from Cyrus and Reese gives you the heart crystals. If you played the wedding game since day 1, you only missed out on 15 crystals. You can probably buy one of each wedding piece even without playing the event every day.
If you've kept up to this point, then I don't think you're missing out on anything except more heart crystals. You could time travel backwards and do the event.
You'll be missing out on the crystals she hands out that day. I'm not sure how many you need to purchase all the items and if playing everyday is a must to achieve this.
I've also missed a day so far but I'm not interested in any of the walls or flooring tbh so it's not a huge loss for me.
Also, even if you miss an important day like the first celebration with the villagers, the game will just pick up from there.