Why is Close Grip Benchpressing easier than the Wide Grip for me?

Wide grip isolates the pecs more. A closer grip allows the shoulders and arms to help more. It's not that your pecs are weak, it's that your pecs are weaker then your pecs + shoulders + arms. Plus, when you are in the down position with a wide grip, your pecs are fully stretched, to basically the weakest point in their range of motion.