Ever reunited with a former flame after a breakup? Splitting and later reconciling is a common phenomenon not only among couples in the early stages of dating, but also among cohabiting and even married couples. (Roughly one-third of married couples have separated and reunited at least once in the course of their marriage.) But as your or your friends’ personal experience may imply, getting back together with an ex carries some risks, according to recent research summarized in the National Council on Family Relations magazine.

Rachel Lindstrom, J. Kale Monk, and Amber Vennum note that scholars once “hypothesized that if you broke up with a partner, but rekindled the old flame, you would be more satisfied because you and your partner had reevaluated the relationship and chosen to renew it.” But surveys of real-life couples with “cycling” relationships prove that’s not usually the case:

On average, partners who have renewed their relationship report poorer communication, fewer positive relationship maintenance behaviors, lower levels of dedication and satisfaction, and greater uncertainty in their relationship, as well as higher levels of verbal abuse and physical violence, than partners who have remained stably together.

The more breakups in a couple’s history, the lower their relationship quality, on average. In fact, relationship quality “declines with each breakup and reconciliation.” And unsurprisingly, couples who have endured a temporary split are more likely to split in the future than couples with a stable relationship.

Citing the work on “sliding versus deciding” of IFS senior fellow Scott Stanley, Lindstrom, Monk, and Vennum theorize that “the lower dedication and greater uncertainty” of reunited partners may arise partly from “less explicit decision making during the initial development of the relationship.” Couples who ignore warning signs and neglect to communicate about problems while moving forward in their relationship end up accumulating constraints, such as a shared residence, that motivate them to stick together or reunite after a breakup despite their problems. Repeated breakups may also lead to greater anxiety about the future of the relationship, which makes it all the harder for couples to communicate well and make prudent decisions.

Like other risk factors, having broken up with a partner in the past does not doom a relationship  to fail. But there’s still an obvious takeaway for those considering getting back together with an ex: evaluate your relationship carefully before renewing it.