TL:DR - What can be done to protect this asphalt from cracking as it pulls away, maybe slow it from pulling away, etc? I'm open to any thoughts on any of it, even just thoughts on why it may be happening.

https://imgur.com/a/dZbVAHZ

My best friend lives in a cul-de-sac and the asphalt has been slowly pulling away from the curb the past few years. The road is sloped down towards the cul-de-sac a few degrees, nothing crazy. The neighborhood was built in the mid-2000s, I believe the asphalt is that age. He would like to know what he can do to slow the problem, does this gap need to be filled and is this just a symptom of land settling over time? The picture is not great but this gap is slowly occurring around the entire bottom half of the cul-de-sac, approximately 30 linear feet. The storm water drain is approximately 10 feet to the left of the picture. Vehicles are not normally left parked in the street in the area in question.

Thank you!