Kansas courts have held that fault is ordinarily not relevant to the question of who should have ownership and possession of an engagement ring after the engagement is broken.  In Heiman v. Parrish, the court opined that ordinarily, the ring should be returned to the donor, regardless of fault.[1]  The court further stated that there may be extremely gross and rare situations where fault might be appropriately considered.

[1] Heiman v. Parrish, 262 Kan. 926 (Kan. 1997)