(image credit: coba)
Playing games as couples is more like an art than science (don`t know why I said that). You have a world that you may or may not want your significant other to be a part of. In any case, there should be games that you can share, if you have to. Mystery Case Files is definitely one of them.
The concept is extremely basic. There is a list of items on the right, and you are trying to find them in the picture. Actually the developers are clever enough to embed this puzzle pieces into a story and the items are not easy to find.
My favorite one was Madame Fate, a twisted circus story with lots of different puzzles in addition to hidden item quests. There are 6 games available for Windows or Mac. After a while, your eyes get crossed, and the fun activity with your partner becomes more like a frustration, where her incapacity to find a hidden item becomes your only focus, you fight, plates crashing on the wall, slamming doors, lawyers and so on..no happy ending in this one.