They both have really strong female lead
And a softy male lead
Another thing is the guy is always caring and loving towards the woman and the girl will always want them to be there for them and always make a promise with each other stay by each other side

because it has the same serious mood
like one main then is one act role will be serious and one role will be childish
but the other is be honest
so like in the ashes of love jin mi is childish and she may have i think the jelous side whenever pheonix gets over work out with her and is serious with her when it comes to things ,and also it seems like there might be some tringle of love going on between them and they always care for each other when they get hurt.pheonix is a chill and serious guy but always like to get things done even like to bebossy.
and in the untamed
wei wu xian has this helpful and careing side of him but he also makes mistakes when something happends
langwangji he always so serious when wei wu xian try to help him or ask him what he should do.
gotta that these both may have the same vibe it just that they both smooth and really good very fanstasy so ya.

sorry if this was not good explaining but ya