Pine table top, well sanded, 3rd coat of stain remains sticky after greater than 12 hours

Depending on thickness of coat, could take longer. Stain "hardens" by polymerizing linseed, tung or similar oils. Did you wipe the coats off 10 minutes after applying? You can try Mineral Spirits to remove some of the stain. Personally, I have never used 3 stain coats, 2 is more typical. High humidity slows reaction times too.