Sometimes, it's just that it seals very good. Have you tried opening the freezer door, than try the fridge door?
Ours is also sometimes hard to open, but I never had it stuck. Sometimes it just requires brute force, but at the same time, one does not want to fall on their behind with a fridge handle in their hand and the door still closed.
If/when you get it opened, I'd recommend cleaning the rubber seal round the door and apply some silicone lubricant spray on the seal, but not on your food. Might be easier to spray on a rag and rub it on the seal.