Mehai0987
Hey if you want to read gangster age gap thriller mystery story then read Tangled desires of Kishori tales. Tropes
Age gap (20-30)
Forced marriage
ML Gangster - FL Law student
FL is orphan but has a brother same age as her husband 30 years and both brother sister are rich
ML is rival of FL's brother
There's a villain who is obsessed with FL.
Hope you love the tropes . Do give it a try. Also chapters are also not so small. You can find the story on my reading list .1st or 2nd story named Tangled desires.