Recommendations

The plot lines are quite similar however they have their own differences.

The female leads travel to past (Goryeo) in both dramas.
Even though there is so many differences between this dramas.

Both dramas are orientated around the complicated relationships within the family though "What happens to my Family?" veers off to have more in depth relationships for each member in the family they both deal with the same issues with "Yeah,that's how it is" being a more serious drama.

The main girl also cross-dresses as a male during a historical period...

it's kinda similar to this drama but that's only with the whole two different world things I recommend reading some reviews.
The drama is about a girl named Claire Duncan who is absolutely addicted to watching her all time favorite Korean Drama "Taste of Love" and wishes she could live in a world exactly like that, when suddenly she finds herself in the so called "DRAMAWORLD" where she meets another facilitator by the name of Seth Ko who's a waiter in which you think wouldn't hurt a fly but is he really all he seems to be?

If you enjoyed the slice of life feel that Age of Youth offered then Dear My Friends is a perfect follow up for it. I would say the obvious difference would be their age, otherwise both dramas have a strong emphasis on friendship and sisterhood, coming of age for the younger set and coming to terms with their age for the older women. Their stories and their feelings are so relatable.

Same revenge stuff. If you liked one, you might like the other one too.

I think they have the same pace and mood. They both
talk about coexistence, friendship and love with a more realistic approach.

Though not as a much of a gem as Splash Splash Love - in my personal opinion - Snow Lotus still managed to touch my heart in a similar way by covering two of the same themes: love, and the blending of the Joseon era with modern day. It's also only two episodes long.

They're both very cute and romantic and the same actor stars in both dramas.

although the genre and the main story feels completely different, the feel of both the shows are very very similar. A boss and a worker love, the whole working group as a gang and friends concept, there's so much comedy in both yet si much cuteness too. Both are refreshingly swoon worthy and both shows are a visual treat to the eyes in terms of the cast!!

In both dramas a mastermind gives his opponent clues in order to uncover the truth they want to reveal. The feelings of both dramas are very similar, with every episode revealing a small part of a bigger picture. Also both dramas star Uhm Tae Woong (although in very different roles).

Both dramas deal with secrets that are slowly revealed through a tv show and a mastermind who manipulates the MC in order to uncover the truth behind them.

Dun reminded me of a supporting character in Scent Of A Woman. She was the female lead's roommate at the hospital and she also had a crush on her doctor and she was quite positive like the lead here. Now that I think about it, she also made cartoons about her handsome doctor and about her life in the hospital.

OMG was she based on the same person?! That is plagiarism (I think). Anyways, if you liked this movie, you would probably enjoy the drama too, as it deals with a cancer patient living life to the fullest.