First of all, congratulations! The two dates I came up with are:

10 February 1840: The wedding date of Queen Victoria and Prince Albert.

10 May 1612: The wedding date of Shah Jahan and Mumtaz Mahal. The names might not be recognizable, but Shah Jahan had a very recognizable monument built in Mumtaz Mahal's honour. A little place called the Taj Mahal.

Good luck in your search!

Alas! Questions so broad get really dumb answers, so they are prohibited under the rules of AskHistorians. I have removed this comment. Man, I wish I could help you - but the question really does need to be tightened. Perhaps something a little more closely confined might be better? Eg "Did ancient Rome have a holiday dedicated to lovers, similar to our Valentines Day?"

Congratulations thought!