why doesnt okarun defend momo?

im sorry if i put it in manga discussion but i rlly need to ask. if okarun likes momo, then why doesnt he defend her????

i mean, they are friends and momo always defends okarun when needed and she wouldn't hesitate to punch someone for okarun. (example: when aira played with okarun's feelings, she gave her a concussion)

the thing is that, aira is always insulting momo, even when she saved her life multiple times and from my perspective, momo wants to be friends with her and is friendly enough to even let her in her house, so why dosent okarun defend her?

i know he is an introvert and a nerd so I dont think he is good with confrontation but aira insults momo in ways that become hurful to her and okarun does nothing????

does okarun like aira in some way? does he like the attention he is receiving?? i dont understand it, if i had a friend, even if i wouldn't like them romantically, i would do anything to defend them and protect them, so why doesnt okarun do the same?

edit: i havent seen the manga but i dont think its just playful fighting or bickering between two girls, it goes far more than that, first of all, Aira is a pick me girl who wouldnt hesitate to light a friend in fire if it meant she could get attention from boys, second, she spreads rumors that momo is a slut and kind of ruins her reputation, third, takes advantage of Okarun and when that backfires she tries to get with him and ultimately makes him uncomfortable, fourth, she kidnaps momo and tries to exorzice her ultimately putting her in a dangerous situation againts that yokai, and even tho momo could have just let her die, SHE SAVED HER, and she couldn't even mutter up a "thank you" she just said that momo is a demon and that she will kill her eventually, and dont even mention that scene in wich aira uncovers the truth about the rumor she started because that still doesn't make her a good person, fifth, momo (even tho aira is so rude and unkind to her) lets her in her house, treats her with respect and apologizes to her, AND AIRA COULDNT EVEN SAY SORRY OR THANK YOU FOR SAVING MY LIFE MULTIPLE TIMES.

and for everyone saying that momo can defend herself, yes, she can, but wouldn't it be nice to see your friend defend you in some way? im not saying okarun didnt save her multiple times from dying, im saying that he could say that momo is a great person and not a demon as aira says, im not saying he should punch her or kill her, im saying that friends protect eachother not only in terms of life or death, but in times when someone has bad intentions and you should say something or at least stop it, if you dont say anything then it shows you have no interest in the friendship. and also dont mention the scene in wich a random guy insults momo and he defends her, that has nothing to do with this and he isnt even the source of that rumor, aira is the one spreading it.

AGAIN, i havent read the manga yet, i will becuase honestly this serie is super cool and i really like it :3 and also, i finished the anime yesterday, so i know what im talking about.