Manthika

I thought this had a lot of potential going into it, because I, too, can relate heavily to having a Second ML Complex from time to time.  What sucks about this one is you find out very quickly that the 'canon' second lead (who becomes the ML in this version) is AWFUL and now I have Second ML Complex for the 'og' ML T_T this is just not cool. 

To break it down without spoilers: the '2nd ML' the MC likes only liked the 'canon FL' when he realized he couldn't have her.  And I'm not about that kinda bs.  The art is pretty subpar and feels empty and the plot is plodding and boring.   I hold no real attachments to the characters, I frankly wouldn't recommend it to anyone. 

It's not like it's the worst story out there, but it feels an awful like someone had a decent idea and just couldn't live up to it at all.  I mean, I've seen some stories where the FL was isekai'd as the heroine before and went for side characters or for nobody at all, so I definitely know what it looks like when it's done well.  This is not it.