Partner relationships, including new relationships after divorce, are found to be beneficial for mental health. However, the impact of their quality remains unclear; this uncertainty applies to past and ongoing relationships between ex-spouses as well. We study the relationship between conflict—in the prior marriage, with the ex-partner, with a new partner—and both positive and negative mental health. Multilevel linear models are carried out on a subsample of 892 divorcees from the dataset “Divorce in Flanders.” Living together with a new partner, either in marriage or cohabitation, seems beneficial for mental health, even in cases of (high) conflict. Nevertheless, conflict places a burden on well-being, especially for women in nonmarital relationships. Ongoing conflict with the ex-spouse is also damaging for mental health. In contrast, prior marital conflict does not relate to lower, but to slightly higher, levels of life satisfaction after divorce.