Turns out, MC is the Readers we made along the way.
Also, I think I'm beginning to tolerate the Incel that is MC. He might be a useless self centered pushover that has a harem basically gifted to him, but at this very specific arc and event, I can't help but feel a bit of respect to him. Fmc is a rental girlfriend, a normal person would've kept it that way. In this specific event and arc, most people (and I personally) would've watch in the sideline with nothing but a few "you can do it!". He could've left her and her (dying) grandma behind, find another rental girlfriend, heck, he even has a "trial" girlfriend that he could date at any time and be done with it. The fact that he try to help another individual in need already earn himself more respect than some of the people I met everyday. Either that or he really really want to bang Fmc, but yknow, all's well that ends well.
Either-way, the fact that he's willing to put in the effort and support a person that he barely knew, bearing in mind that their relationship isn't the best, is at least admirable. Mc is indeed a stooge, he's a wimp, he's a useless beta-fag, he's far from an admirable MC that you can self insert into, heck you DON'T want to be him, if I know him as the person who date a rental girlfriend even though he already has a (potential) girlfriend and lies daily to keep his ego in check, I would've kept my distance from him. But as a person who went into a rabbit hole, foolishly doing so despite the danger, for the sake of someone he barely knew? He would at least earn my respect,I would call him stupid and laugh at his hubris, but at least deep inside I respect him.