are we okay being alone in our 40s

hi,
I'm 18 years old and my parents are in their 40s. it's been roughly two years since they last slept together. they barely talk to each other and whenever they do it ends up in a fight. but that's not the problem. the problem is that they seem to be perfectly fine with it. they live as though nothing is wrong. I mean no anxiety, no depression. something should show, right? but they do just fine going about, minding their own business. that brings me to question the existence of love. is love just a trivia we feel in our teens and our 30s? is it really just advertisement bullshit we've been fed for so long to know the difference? is love a necessary factor in our lives like they say it is?
also, it must be obvious that they haven't had sex in a very long time. I've also read somewhere that sex hormone production decreases during middle age. that brings me to another question. sex not all about love, but is love all about sex? is love something that disappears along with your hormones? I feel like real shit to talk about my parents' private life like this but this is the only place I can do so. please share your views.
NB: feel free to call me anything you want in the following threads. I, for one, think that I'm a sadistic fuck.