One thing I haven't seen mentioned is that the kinship changes—depending on affection. There are a few levels of kinship for every monster girl. Not a feature worthy of throwing a parade for the developer, but it's nice touches like this, which made me really enjoy the game despite the MC.
As I have previously indicated, wimpy MC's is not to my taste. I don't think the MC is as such per se. Having his best friend and only "family" being taken from him, it stands to reason, why for a while he would be sad. With the encouragement of his fairy buddy he musters up the strength to move forward and save his friend against the odds. He is not powerful in and on himself, he needs help as a "dominator type" of "adventure". Those monsters which he "dominates" becomes stronger in his company, this is the way he fights. I'm not the biggest fan of this method, but I like the customization to the party composition and game mechanics it presents.