Objective: The present research examined whether people with lower self-control were more likely to act in accordance with their sexual desires in romantic situations. Specifically, we tested the hypothesis that sexual desires would be positively related to infidelity and courting intentions, but only when self-control was dispositionally low or temporarily impaired. Method: In Study 1, 331 participants who were recruited online completed survey measures of dispositional self-control, general sexual desire, and past infidelity. In Study 2, 120 undergraduate students were randomly allocated to either a depletion (low self-control) or control (high self-control) condition. Following the self-control manipulation, all participants completed implicit and explicit measures of courting intentions, and indicated the likelihood they would cheat on a long-term partner in an imagined scenario. Results: Study 1 found that sexual desire positively predicted reported infidelity frequency for people with low, but not high, dispositional self-control. Study 2 found that stronger sexual desires predicted increased infidelity intentions, sitting closer to an attractive stranger in an imagined scenario, and asking this person out in a hypothetical encounter, but only among people who had been depleted of their self-control resources. Sexual desires were unrelated to all constructs when participants’ self-control was dispositionally high (Study 1) or not depleted (Study 2). Conclusions: Our findings suggest that when self-control is high, sexual behaviour may be largely divorced from desire, relying instead on analysis of situational or other cognitive factors. Sexual behaviour may reflect genuine sexual predispositions, however, when self-control is dispositionally low or temporarily depleted