I'm pretty sure he didn't really fall in love, he just considers her as a friend(like the other guy with blue hair), it's just that since he didn't have friends in his previous life, MC views his friends as precious.
Also, while it is true that Ning Er can be annoying at times, the fact that MC doesn't want to lose her and is willing to go through torture for her shows how much he changed and how much sentimental he became since he took this body, he even empathize this by saying something like "to think I would go to such means for an ordinary girl"
The point of reincarnation plots is to show how much the protagonist evolves in a new environment and improves (not in terms of skills in general but in terms of humanization) and also to take revenge if he was reincarnated in the same world.
Ooph I understand how you feel.... I kinda feel like the first cast of characters where tossed aside when this second plot opened up ... I'm excited to see his power growth... But honestly would have loved if he had choose to power up because of wanting to still be the best and because he finally was feeling small forms of friendship.. he doesn't need any form of female love intrest. I like that he kinda brushed off all of that previously because he had no need to accept the bullshit that came with it q.q now I'm unsure if it's worth keeping up with the reads.... If anything I wanna atleast read the fights :( does the romance hit heavier later on or does it stay focused on him and his battle to get stronger??
OMg I am honestly so SO dissapointed!! At first I really liked the MC's character and personality and I was hoping to see more of him being OP and cool-headed, not getting interested in any female characters. So I went and read the chinese novel and OH GOSH NING-ER I"M LOSING MY BRAIN CELLS BECAUSE!! HOW DUMB CAN YOU BE??? (I was getting a bit hopeful because the latest manhua chapters showed some good chara dev. but alas!) and MC?? I had so much hope for you??? And you went and become A DUMB SHIT BECAUSE OF SOME INSIGNIFICANT FEMALE CHARAC ?? SERIOUSLY? you were so smart AND YET YOU GOT SO EMOTIONAL AND FELL INTO AN OBVIOUS STUPID SCHEME?? OMG imma go flip all the tables i can find
I'm sorry for ranting so much here. I was so excited when i started the series cuz it looked like it has potential. Went and wasted my time reading bout 200 novel chapters to finally drop it in anguish. gosh, what a waste of brain cells. Some authors seriously need to get educated on how to write a good female character *SIGH*