A common plot in soap operas is the rape of a character, and usually by a character who faces no consequences for his actions. This was more common back in the 1980s (and before) than today because of how we view and treat rape/sexual assault today. Even though we would be horrified by such treatment of rape today on television, it was horrible back then.
There were three rapes on Dynasty/The Colbys and none of the perpetrators faced any consequences for his action. Further, the rape itself did not drive any sort of plotline. It seems that it happened just to have something happen.
In Episode 7 of Dynasty “Krystle’s Lie” - Blake becomes angry with Krystle because he wanted to have a baby and he learns that Krystle has been hiding the fact that she has been taking birth control. The angry Blake rapes Krystle as a result of her deception. (Note, how the episode is entitled Krystle’s Lie and not Blake’s Assault) The following day, Blake feels guilty for what he has done and apologizes to Krystle. It is referenced here and there (particularly after Adam rapes Kirby). Regardless, the question remains, why have Blake rape Krystle?
Blake tries to apologize to Krystle after raping her
In reality, the rape could have explored the larger issue of marital rape which at the time was not illegal in many states - including Colorado (if the husband and wife were not separated). Before the mid 1970s, a husband could not be criminally liable for sexually assaulting his spouse. (assuming they were together in some states, other states had no exceptions). Throughout the late 1970s and 1980s, the laws were changed to recognize marital rape as a crime but there were still loopholes in the statutes that were eventually cleaned up. However, that discussion did not happen. Basically, Blake raped Krystle (even if not a crime at the time), she eventually forgave him and that was it.
Similar to Blake, Miles raped Fallon while they were married. At that time, the act was likely a crime in California since Fallon resisted (a requirement for California).. Still, the only consequence Miles faced was physical violence from Jeff which became more intense when there was the prospect that Fallon could have become pregnant as a result of the rape. At least this time, all the characters involved referred to it what it was - rape. Still, Sable did not seem to care that Miles raped Fallon when she learned that it could have resulted in Fallon’s pregnancy. Miles being the father of Fallon’s baby was more important the act of conception.
Finally, we have Adam and Kirby. Adam’s rape of Kirby was the most violent (not that violence matters) and everyone in the family seemed to not care - other than Jeff who of course got into a fight with Adam. Kirby never went the police and no one forced her to do so (there are probably class issues involved here). In fact, when Kirby discovered that the rape resulted in her pregnancy, Adam wanted to do the the right thing by marrying Kirby - which is what Adam wanted all along. Basically, by raping Kirby, Adam almost got what he had wanted.
In the end, these rapes seemed gratuitous and are actually harmful. Yes, it was a different time, but to allow three main characters rape three other main characters and have nothing happen (other than the occasional chastisement or feelings of guilt) really does a disservice to any discussion of sexual assault. Obviously, you cannot ship Blake, Miles or Adam off to jail. Then, don’t have them be rapists.