Sexual satisfaction is an important component of relationship well-being within romantic relationships. Yet, relatively little is known about the psychological factors that predict responses to the inevitable sexual challenges couples face. Four studies provide evidence that implicit theories of sexual attraction as either fixed or malleable predict responses to sexual challenges. In Studies 1 and 2, individual differences in these beliefs predicted (above and beyond other implicit theories, relationship beliefs, and measures of sexual desire) perceptions of success for a relationship lacking sexual chemistry. In Study 3, these beliefs predicted actual relationship outcomes in committed couples. Finally, in Study 4, these beliefs predicted willingness to engage in destructive behaviors in response to a sexual challenge—but not in response to a non-sexual challenge—in a hypothetical long-term relationship. This latter finding was mediated by expectations that the problem faced by the couple was solvable.