In the middle of reading I thought that this idea of 'trying out' different girls (who may or may not remember things between loops) like some kinda playboy is only good for causing heartbreaks for everyone involved.
Of course the author was one step ahead and things got more screwed up than I could imagine.
So he died or is comatose (prev chapter the other girl had a hospital scene flashback) and she wished for him to come back/whatever happened to never have happened, hence the loops so that it won't lead to that future?
but it is still accepting her wishes? is it her power? or is it because the changes are against the original wish, hence the reset.
I think different people are controlling different people's loops.
MC's best friend is most probably controlling MC's loop. Because each time MC sacrificed his feelings and got his childhood friends together he looped, so just like this maybe the friend felt really bad that his best friend (MC) had to kill his own feelings so he didn't want to get together with childhood friend hence resetting the loop to 7th may.
Now one time MC actually confessed and whatever the result was, I think MC's best friend was kind of satisfied that at least MC got his feelings out so MC didn't loop that time.
Now this current loop was triggered by female childhood friend. I would go as far as to think that the previous loops were triggered by the blonde female and she most certainly lied to MC a couple times but I don't see the reason how she is involved in this.