Leather seats, crack in leather on side.
 

The front driver side seat cusion in our 2007 Aspen has a slight crack from wear. This is where we slide out of the vehicle and apparently from being compressed so much it is cracking, it is stained slightly blue also from jeans I guess.

is there a way to prevent this crack from spreading? or to repair the leather?

Whether you want to make it last a little longer before addressing the problem, just remove the jean stain (if possible), or sand and refinish, the answers are here:

Home Page | Leatherique Restoration Products

It's the best product I've tried for leather, and worth every penny. Follow the directions and you'll get great results.