Both dramas involve an accidental pregnancy and contract marriage that brought the leads closer. The female lead in sunshine happiness wanted to save an orphanage and the female lead in fated to love you wanted to save a soap factory and her hometown. Both female leads are both caring individuals who puts other's needs and feeling first. This traits endeared them to their respective male leads.

Both are stories of cohabitation. The female leads are both older career oriented individuals who are initially in love with another guy. Through shared experience and interactions both couples fell in love however the female leads are slower to catch on their feelings. The female leads eventually realized that they cant live without the male lead when the male leads disappears.

both are rom com although wild romance had an added mystery component to its story.
If you are already tired of the cinderella transformation of female leads in almost every drama with the mandatory make-over scenes, then these dramas are for you.
Both dramas shows that the female leads need not change her appearance to catch the guy. They'll be love just the way they are.

Both dramas are fluffy rom-com. Both dramas involve an older female lead who both suffer dating and marriage deadline woes. Both involve handsome and adorable younger male leads.

Both dramas also tackles leads being bitter because they were left behind by former lovers without reasonable explanations. It depicts how this new love interest had drawn them out of their bitterness.
Also both dramas showed that first love is not cast in stone and eventually changes or disappears when out of sight or not nurtured. One's heart can change over time and choose another person. First Love may not be the best love that will come your way.

Both have an older female lead with an abrasive personality who softens and transforms to a better person due to the love and influence of a younger and affectionate male lead.

Both dramas involves a female lead who were spoiled rich air heads that eventually transforms via great character development through series of trials, as they eventually try to develop their knowledge on their respective careers.
Both male leads in the drama are both conflicted with the dilemma that they should not fall in love with the female lead. Both dramas have revenge plots but eventually the male leads falls for the female lead and end up protecting the female lead. The female leads gets hurt by the knowledge of the background of the male leads but eventually could not resist loving the male lead despite his background but accepts him as himself rather than from where he is from and what he has done in the past.
If you love dramas that tackles on "Love that should not be" and "Love overcoming Hate" then both of these dramas are for you.
PLUS both leads in both dramas have AMAZING CHEMISTRY.

Both involves an older female lead who had cynical rough attitudes brought about their experiences as they grew older. Both dramas have younger male leads who loved and cherished the female leads in their hearts since they were kids.
Both dramas involve cohabitation and the sweet interaction brought about by this and how eventually the female leads realized how they can't live without the male leads because they are so used to it that they have taken it for granted before.
The love between the leads eventually changes the female leads character for the the better whether it be on her outlook in life and love.
both male leads are adorable with their pupply love and wearing their hearts on their sleeves. Swoon worthy if you like noona romance.

Both series are good rom-coms that are delightful to watch. They have both have male leads with weird eccentric personality but eventually becomes adorable. The male leads both see something special to their seemingly ordinary female lead and its a fun watch how these alpha males becomes soft hearted because of their love for the female leads.
Both also had used the machination of amnesia in their story plot but don't worry because the male leads quickly got their memory back and lasted for just an episode. Its seems love has a way of bringing memories to surface.
Both dramas also used metaphors like sun, shield and snail... you'll get these after watching and will become fond associations when you think of these dramas.