Mating bears large costs to females, especially in species with high levels of sexual conflict over mating rates. Given the direct costs to females associated with multiple mating, which include reductions in lifespan and lifetime reproductive success, past research focused on identifying potential indirect benefits (through increases in offspring fitness) that females may accrue. Far less attention has been given to understanding how costs of sexual interactions to females may span across generations. Hence, little is known about the transgenerational implications of variation in mating rates, and net consequences of maternal sexual activities across generations. Using the seed beetle, Callosobruchus maculatus, a model system for the study of sexual conflict, we look at the effects of mating with multiple males versus a single male, and tease apart effects due to sexual harassment and those due to mating per se, over three generations. We show that across generations, harassed females suffer a severe decline in fitness compared to non-harassed females, while multiply mated females showed no difference in net fitness compared to singly mated females. Overall, it appears that the transgenerational benefits of multiple mating counteract but do not exceed the direct costs of harassment. Our study highlights the importance of examining transgenerational effects from an inclusive (looking at both indirect benefits but also costs) perspective, and the need to investigate transgenerational effects across several generations if we are to fully understand the consequences of sexual interactions, sexual conflict evolution, and the interplay of sexual conflict and multi-generational costs and benefits.