TMZ Sports is told Holly Sonders -- who went public with ODLH back in August -- initially thought her man was blowing off the special day with a TV show filming and a round of golf with the bros ... leaving behind a Hermes bag and a diamond bracelet to make up for his absence on the special day.

As it turns out, there was one more gift -- an even bigger gift -- on the way ... and when Oscar got home, he told Holly to go out to the garage.

That's when the big finale was unveiled ... a beautiful red Ferrari SF90 Stradale was waiting for her -- with a bunch of roses sitting on top!!

Check out the vid -- Holly is clearly thrilled with the gesture ... recording herself as she takes a seat in her new whip.