Although Scrooge lost a great love--the scene earns a song in The Muppet Movie--few versions reunite him with that great love. Likewise, The Grinch doesn't start dating at the end--not in the picture book or animated feature. And although Russ from The Kid has a girlfriend/wife waiting in his future, his change is due to a visit from a "ghost of Christmas past," not the potential significant other.
The difference lies in the character arc. Scrooge and The Grinch and Russ undergo an internal realignment. The internal change is shown through external images and events. The stories are quite remarkably well-told.
With Groundhog Day (also a great film), the change is about the main character learning to get along with other people.
Scrooge alters internally and shows that internal alteration through his treatment of others.
Phil learns how to change internally by treating others, even a life insurance salesman!, better over time (one day over and over).
I think that both types of change/epiphany are possible. Romance is more suitable to the second type than the first. The Beast learns to be less beastly by spending time around Belle.
Scrooge learns to be less awful through forced personal reflection.
