"Amateur Granny Enjoys Big"
The phrase appears frequently as a descriptive title or series name in adult-oriented niche erotica. If you are looking for a detailed guide to relationships and romantic storylines featuring older protagonists, Core Storyline Tropes
If you are looking for deep reports on specific storylines involving grandmother characters and significant relationships:
The "Secret" Romance:
A common theme involves a relationship kept hidden from family members or societal expectations, often set in locations like nursing homes or small communities.