L'amour éternel (2017)

Both are dramas with a modern day FL who is magically transported to historical times where she meets and falls in love with the ML.

The female protagonist time travels to the past. However, this is part of her job as she is sent on "missions" to certain historic eras, so the drama overall does not become boring. The protagonist is also considered to be odd/unique to those she meets in the past since she is from the future. She also has a past life and there is a underlying secret to her life.

The eternal love is also about time traveling and the female lead is also from modern times the female lead and the female lead from the another universe swap souls everytime she hits her head

Both are light dramas with a modern day FL in a historical setting, and a prince ML. Both princes suffer from illness or poisoning.

A quirky FL from the present day ends up in the body of a different girl in the past and has to live her life (dealing with a fiancée, etc.). Both have a fluffy, fun feel with a few serious moments.

Fluffy dramas with a time traveling modern day FL forced to marry a historical ML. The couple clashes at first but soon falls in love.

Both are dramas with a modern day FL who is magically transported to historical times into another girl's body.

In both dramas there is a prince and a spunky girl who get married early on, but the couple takes some time to fall in love and live as a married couple. They both have some palace politics and the struggle for the crown prince position.

Both have a modern day FL transported to the past and a ML who is supposed to only have a short life.

The leading man, in both dramas, is sought after by many women but he show zero interest in any, until he meets the leading lady, who is like a breath of fresh air. The leading lady, in both dramas, are adorable, energetic, and independent.
The leading man is decisive and is the pursuer. Since the leading men in both are irresistible, the leading ladies fall easily for their good looks and charm.
Even though Love O2O is not a fantasy drama, it does have a fantasy element, with the video game they play. The game element also allows this modern day drama to include a bit of the traditional Chinese clothing and hair styles.
Main differences: Be aware that in The Eternal Love there are some really cheesy special effects.The Eternal Love has a backdrop of Royal politics/Sorcery.
Love O2O has a back drop of social media/College-life/business.

Both are fantasy dramas Both have adorable, somewhat mischievous leading ladies.
Both have an element of the couples uncertain future, since they "from two different worlds." One is literally a different world and the other is figuratively, but that fact threatens the happily ever after of both couples.

Both are dramas with a modern day FL who finds herself in history. Both MLs are royal.
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This is the first season to watch to get a better understand if you only jumped onto season 3 without watching the previous 2. it's a fun series to watch, its slightly a confusing ending but it works well with the season 2!

I recommend this both drama because , Male lead and Female lead
try to solve problem
In one drama explosion and another student murder/suicide

The FL in both dramas is Liang Jie
Both dramas have body swaps ( one between the ML and FL, the other one FL with the real body owner)
Both are really romantic and have great chemistry