Zactly. A character who doesn't have a love interest for the entire duration of the novel would seem a little odd to me, since most of the people I know have private lives that revolve around romantic relationships in some way.
This, I think, can be a fine line. f you are writin a sprawling epic and not one of teh dozen people you have as MCs even
looks at anyone else in that way...Some people are asexual. Cool and fine. The whole cast? Unless you have a reason for that...
On the other hand, perhaps their behind closed doors shennaigans do not figure into the plot. I can see that for one MC in a single POV novel
It depends on the scope of the story -- if you are following one person, fair enough. Maybe they are caught up in the plot. or are asexual or any number of things. If you are following five...it starts to look odd if
none of them have any romantic leanings. Especially if they are of a younger age. It looks in fact like you have just excised part of their personality (again is they are asexual then that's also fine and part of them, but ALL of them? I need a reason)
Because, let's face it, listen in on a teen's convo. Almost any teen, male, female, straight, gay or trans. There is a strong possibility one of them will say "X? Oh Ma Gerd" (as my daughter would say). If the unattached people in your novel do not at least think "oh, nice" when meeting someone of the gender of their choice...
Attraction/lust/love is not universal but...
It is part of who people
are. Ignore it at your peril
And I could also point out the fact that when men write about love it is meaningful, but when women do it is fluff...