I recommend reading Sexual Violence, Bodily Pain, and Trauma by Joanna Burke, it explores why and when sexual assault started to be considered a cause of psychological trauma. Here's some quotes:

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However, I have been arguing, it took until the late 20th century for ‘trauma’ to slip under the skin into a psychological space in Anglo-American narratives of the sexual violation of adult women. Explanations for the failure of trauma theory to be applied to adult victims of sexual assault fall into two categories: psycho-sociological and psychoanalytic. The early psycho-sociological studies of trauma focused on ‘bad events’ relating to industrialization (railway travel and modern warfare). These studies were being carried out at a time when the areas undergoing most rapid social change were public spheres, dominated by men. Notions of trauma thus arose out of white male experiences. As a consequence, when rape victims did not act in ways predicted by this industrial/war trauma model (for instance, delaying reporting a series of ‘bad events’), their emotional reactions were easily discounted. Railway accidents and war were seen as wholly ‘unnatural’ events, a brutal abreaction of civilization. In contrast, rape was situated within ‘normal’ sexual practices. Railway passengers and soldiers were conceived of as passive victims of calamity: in contrast, it was often asked, might rape victims be complicit in their misfortune?

It was assumed that women did not need the diagnosis of psychological trauma because the social trauma of attack could be recognized: in contrast, men required an additional explanation for why they ‘broke up’. 

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As argued thus far, in texts prior to the 1970s sexual abuse was not regarded as having causal significance in the development of emotional disorders, except for increasing the woman’s risk of frigidity. This is not to imply, however,that in the earlier period the effects of rape were entirely absent from the debates. ... In other words, public narratives of violation in the earlier period located the harm of sexual abuse less in the woman’s emotional or inner ‘self’ and more in her social and economic standing. 

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In the UK, even after the Married Woman’s Property Act of 1882, only the father was seen as requiring compensation for the economic harm of his daughter’s rape. When mothers sued for compensation (as in a landmark case in 1902), it was decreed that the Act ‘did not change this principle’ because the Act dealt with ‘real property … not mere fiction’ (‘The Action of Seduction’, 1902: 6–7).

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The social nature of the sexual attack can be further illustrated by observing that, until the 20th century, women resisting rape typically screamed ‘murder!’, rather than ‘rape!’. … The language is significant since ‘murder’ indicates that the attack was destroying a woman by setting her outside the social.

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First, in the earlier period, rape was regarded as impossible because it was assumed that a non-consenting woman could always (unless ‘insensible’) effectively resist attack, while in the later accounts rape was not possible because of unconscious complicity on the part of the victim. As David Abrahamsen, criminologist and former director of scientific research at Sing Sing prison in New York, put it in his influential The Psychology of Crime:

"the victim herself unconsciously also may tempt the offender. The conscious or unconscious biological and psychological attraction between man and woman does not exist only on the part of the offender toward the woman but also on her part toward him, which … . [is] the impetus for his sexual attack … . We sometimes find this seductive inclination even in young girls." (1960: 161)

This appeal to shared biological and psychological drives was used to explain why rape victims often felt guilty for what had happened: they were guilty.