Well i started feeling that way after she had put a lotttt of mental and physical strain on herself just to get back to her boyfriend and overall too about how much involved she is and sensitive towards his problems and issue's but so far i haven't come across a chapter where the male lead reciprocates the same depth of concern and affection towards her his side seems more like a normalish pretty generic relationship types....just my opinion tho feel free to correct me ╮( ̄▽ ̄)╭
Like it pissed me off when he was being super freaking moody and mean when she came back without even understanding her situation or trying to listen to her side i felt like the chasing arc was soooo pointless any sane person wouldn’t react that way and just showed the depth of the female leads feeling's and how petty his are. Same goes with the whole saving money thing she was so damn considerate about it didn't bitch or moan and without making it obvious made adjustments whereas he didn't even find the need to stop capping till she started putting herself thru shit and he had no other option.
A relationship goes 2 ways. The fact that you only empathize with the FL and her issues and her struggle bc she is the main person we were with during the gap- it's understandable that you think ML is "not good enough" but it is not rooted in reality. He was moody for a day or two. And not bc he was genuinely mad at her but because he felt abandoned and untrusted in her life. People are allowed to have personalities beyond pleasing their partner. I urge you to look at this from a different perspective. Juan's job is not to be the perfect boyfriend. It is to love Yujin. He does that and he shows that even when he is upset. It shows in how he didnt even know how to react instead of outright being pissed. He doesn't need to immediately be okay with what happened. It was hard on both of them. But at the end of the day he was the one who didnt know wtf was going on, not her. And he still waited and still waited. This is the greenest of green MLs and you are still finding a reason to dislike him. I personally believe you just don't like men who have personalities. And maybe that is okay. But it is not realistic nor rooted in emotional intelligence nor logic.

I lowkeyyyy feel she's too good for him...just my opinion