I found this post about ‘for beginners’ quite interesting. I could see a learning curve being explored and that would have to be approached in a particular way i.e. building a palate. I would start with some of the short stories of M. T. Vasudevan Nair. The way he conveys repressed emotion and unspoken tension in his stories is masterful. ‘Vanaprastham’ (the story and not the film) is a great example of a quiet, aching sort of sensuality which would allow the beginner to experience and learn to appreciate subtext before graduating to more obvious narratives.
I wouldn't trust any app that promises this exact combination. I suspect most such apps are looking to extract value (or information) from you and will deluge you with a barrage of ads. It’s far safer to go with large, established platforms that do have Malayalam audio and let you browse through for more mature romance stories. Yes, you might have to trawl through more stuff but it’s far safer, far more ethical and will give you a far better user experience in the long run. Kuku FM and Spotify are traded on the stock market or are large companies with reputations to uphold. A small app called ‘Malayalam Hot Stories Audio’ has no such reputation.
Use your secondary email address to sign up for any service online and avoid linking social media profiles. Be extremely cautious when a service asks for permissions to access data, etc. It is highly likely that the best audio content for mature romance stories in Malayalam are on the following services: Kuku FM and Spotify. They have a large audience and professional creators to serve that audience. Shady standalone service that seems too perfect to serve your niche, sensitive desires online are best avoided.
Honestly, most of the Kannada content available online is fairly plain. For more meaningful tension, I deliberately avoid stories labeled as ‘sex stories’ and look for romantic fiction that’s been described as ‘mature’ or ‘slow-burn’. There’s this one story, ‘Mouna’ I think, where a married couple live in silence. Eventually the wife starts leaving notes all over the house for her husband to find, with increasing degrees of desire expressed. It was really hot because it was all about the wait and trying to read between the lines. Such content is written by Kannada authors and can be found in online forums. Most of them deal with the human mind as the ultimate erogenous zone.