Here are three classic Shakespeare plays to get you started with some ideas.
Romeo and Juliet -- Can you have characters who come from opposing sides of a feud, a war, businesses, etc? What if they meet without knowing they shouldn't be together and in that chance meeting there's a spark? You now have a classic framework for a great plot.
Much Ado About Nothing -- Matchmaking between two people who not only despise love but also each other. Sounds like the beginning of a good Christmas story!
Taming of the Shrew - A father wants to marry off his two daughters but he can't marry off the younger daughter until his grumpy older daughter finds love -- a handsome man, Petruchio, takes on the challenge to try to "tame" the "shrew." You could flip the gender or play around with other plot elements to this to make it less sexist, but it does sound like a classic romance plot... because it is!
