We have some redundant tags.
We ought to decide which form should be standard, and alias the others.
groping_*generally has more uses, but very few tags on either list have existing aliases or implications. To make things even more confusing, pec_grope is currently aliased to pec_grab, but groping_pec is not. This raises a related debate on the difference between grope and grab.
If it matters, the related fondle set has already been standardized to the fondling_* form with the exception of self_fondle.
Personally, I am not sure which is better, other than that I think self_grope should remain as-is for consistency with self_fondle. *_grope sounds "neater" to me in some indefinable way, but groping_* is better for listing, since it groups all grope-related tags together in an alphabetical list.
Updated