Why your hand gets tired as you finger your girlfriend?

Your hand may get tired while fingering due to the repetitive motion and muscle fatigue involved in maintaining a specific position for an extended period. The muscles in your hand and forearm can become strained, especially if you're using a lot of force or are in an awkward angle. Additionally, tension and excitement can lead to tighter grip and strain. Taking breaks or varying your technique can help alleviate this fatigue.