Is this a good excuse to skip a party?!
Answers:
Best Answer - Chosen by Voters
Its kind of hard to say. Maybe ask them? Either have fun and party hard!
A perfectly good excuse and Great for them for maintaining their date nights!
You have no idea what their story is, they might be having relationship trouble and need the date nights, they might just like spending time together and look forward to date nights... or they might just not want to attend your party for whatever reason.
If they consistently decline invitations from you, then I would no longer invite them - not to make a big deal out of it though.
Whatever their story is, don't worry yourself over it - focus on your party and Have Fun!
Life experience
Its sweet that a married couple is still adhering to a "date night." You never know, maybe they haven't been able to make the past few Saturdays work out. I wouldn't take offense.