from the looks of this chapter (and the flashforward chapter), it feels like daisuke answers their loves with a different kind of love instead: to be exact, friendship love. serious, husband-and-wife(s) romantic love wouldn't make sense if we're considering the flashforward chapter, because in that chapter, they look nothing like (harem) couples. so technically, rejection (and substitute as compensation). but that's just my own personal take
but describing it as "cowardly ending" is silly. this manga is never that serious to begin with, with all their shenanigans of "are ghosts exist?" debates, brute force magic, hypnotism, extreme chemistry, silly ecchi-harem moments and everything else in-between (i honestly lost count of how many valentines, white days, summer breaks, christmas days, new years eves, etcetcetc, have all happened throughout the manga from beginning to end — you'd think that kotone would have long graduated already). now we're suddenly demanding a serious and/or bold decision of daisuke's (or the mangaka's) whatsoever?
of course you lot would be disappointed. you set yourselves up