Where ML used to be good person but after a sad and angst event happend to him (for examples he lost his family or his love of life) he turns into cold and heartbroken person....

FL is supportive to him and wanted to help him...

Ik this is rarely heppend to find  dramas like it  ..but plz help me...

The dramas which had this elements were East of eden,The princess man, Jeosung gunman and Innocent man

  • Doctor Stranger (ML really is a good person but due to his circumstances and traumatic event in childhood it forces him to do bad things) Doesn't fit your requirements that much but might as well throw it in.
  • Just Between Lovers
  • Moon Lovers Scarlet Ryeo (Between IU and Lee Joon Gi)
  • Radio Romance (ML isn't completely cold but he his depressed due to his circumstances and childhood but FL is always there for him to cheer him up)