In Gurney v. Gurney, 899 P.2d 52 (Wyo. 1995), the parties stipulated to shared custody alternating every six months. Id. at 53. A short time after the decree was entered, the mother moved to a different town and the father petitioned to modify the decree. Id. The district court granted the father's petition and awarded him primary custody, which decision we affirmed. Id. at 56. The concurrence took exception to the district court's consideration of mother's pre-divorce and pre-marriage romantic relationships at the modification hearing. Id. at 56 (Lehman, J., concurring in result). The Court held: "Here the stipulation for joint custody included representations by the parties that sharing of custody was in the best interests of the child, and those representations were made by the parties with full knowledge of each other's history. A party, based on that representation, should be estopped from later arguing at a modification hearing that the other party should lose entitlement to joint custody because of premarriage and/or predivorce lifestyle. The determination at a modification of custody hearing to go back into time to revisit a party's predivorce, and in this instance premarriage, lifestyle seems obtrusive, especially where no connection was made depicting how the premarriage lifestyle relates to the present lifestyle or parenting abilities." Id. The Court held that when both parents inform the court that a joint custody arrangement is not working, a sufficient change in circumstances justifying the reopening of the custody order had been presented to the district court. Id. at 55. In affirming the district court's decision to award primary custody to the father, the Court noted that the mother had correctly noted that her relocation to another city was not, in itself, a material change in circumstances. Id. However, the Court noted that the districtcourt could have reasonably concluded that the conditions resulting from the move contributed to the parties' inability to agree and communicate, which were sufficient to constitute a sufficient change in circumstances. Id. at 55.