Prison World series
This is a four book series consisting of two duets that are related but can be read separately. Each book/duet features a separate group of one woman and four men. The events take place on another world, with different society rules. The sex is steamy and consensual and each book ends in a HEA (Happy Ever After).
Recommended Reading order
Guardian Wolves trilogy
This reverse harem series consists of 3 books involving the same set of main characters throughout as they travel their journey from finding one another to discovering who they are and how they need one another .