Title: Gender Role Flip and the Echoes of Regret: A Comparative Study of 'Ex-Husbands Regret' by Evelyn M M and 'Incomparable Son-in-Law'

Ex-Husband's Regret invites readers into a deep pool of emotions and lessons. The novel takes you on a journey through an engrossing chronicle of two characters staring at the shattered remains of their marriage in its aftermath. It leaves no stone unturned, exploring what happens when a momentary lapse of judgement drastically shifts the course of two lives forever.

Part 1: Main Storyline of Ex-Husband's Regret

As we excavate the core narrative, we're bestowed with two characters, Ava and Rowan. Their lives steer down a tumultuous journey, all stemming from a fleeting decision made by Ava years ago. Love brewing since childhood pushes Ava to a decision that seals her fate in a loveless marriage with Rowan. As they claw through their realities, they grapple with a desire for escape.

Leap forward nine years to bustling streets of the present day, we find Ava worn thin by the uneventful monotony of a passionless relationship. She yearns for liberation, leading her to file for divorce. But this decision is not an isolated event. It spirals into a domino effect, pushing Rowan on a collision course with his past and the repercussions of his own actions. It unfolds a riveting drama entwined with themes such as self-discovery, redemption, and the relentless pursuit of genuine love.

Part 2: Main Genre of Ex-Husband's Regret

The novel is etched in the far-reaching segment of contemporary romance, a subgenre that vividly maps the labyrinth of modern relationships. It seamlessly combines components of drama and heartache, engulfing readers from the inaugural page till the final full stop. Despite the pulsating theme of romance, the book interlaces aspects of complicated family dynamics, personal growth, and the indelible scars left by spontaneous judgments.

Part 3: Plot Expectations in Ex-Husband's Regret

Prepare to be drawn into an enigmatic plot, where past ghost haunting the present is a recurrent theme. Anticipate an exploration of forgiveness, redemption, and the potential rebirth of love after heartbreak. As Ava and Rowan navigate their turbulent lives, the question of rightful companionship emerges. Expect a deep dive into their emotional whirlwind, providing a comprehensive view of their internal strife. As the plot thickens, tensions may escalate and both Ava and Rowan may be compelled to revisit their decisions and evaluate their abilities to amend past missteps. Hold on for a thrilling journey, complete with love-triangles, do-overs, and the surprising search for happiness amidst adversities.

Part 4: Conclusive Remarks

To encapsulate, Ex-Husband's Regret promises an emotional rollercoaster surpassing traditional romance novels. Bound to leave a lasting imprint, the book intricately dissects love, regret, and redemption, presenting compelling narratives that provoke a deep thought process amongst readers. This is a must-read fits the bill perfectly, fusing the candor of romance with the formidable trials of real life.