By education. People need to be educated about healthy relationships and the importance of consent. Schools, families, and society at large should promote the values of equality and respect in relationships to counter such harmful ideas.
We can prevent the spread by promoting positive relationship models. For example, highlighting relationships based on mutual love, respect, and equality. Moreover, we should encourage open discussions about healthy sexuality and relationships. By creating a social environment that values ethics and human rights, we can make it less likely for such harmful ideas as in 'couples sex slave stories' to spread. This also involves challenging any form of misogyny or power - abuse - related ideas in society at every level.
One way is through strict laws. Laws should be in place to punish any form of exploitation or non - consensual behavior in relationships. Also, media and social platforms should have strict policies against promoting such ideas. Additionally, community awareness programs can be carried out to make people aware of the unethical nature of such concepts.