This story is not about emotions at all, and it also isn't emotional. Emotions are used to justify strands of plot, but in the end the whole story is about the perspective of the onlooker. It's about the tragic tale of how everything is just an illusion created by the brain, fed by information coming through your senses, and fit together to create what we call "reality", where in fact everything is relative.
What people think,feel,say and do are things we perceive without context, the influence our view of reality but in their reality the reason and result of their thoughts,actions and perception is different from ours,the onlooker.
Every single instance in the story uses the same paradigm, and every character wants to run away/cut off ties with others because of their realities clashing hard with each other, resulting in the other always being "wrong" or "bad".
I won't go into detail here because it would spoiler everything potentially, but for those who've read the story, they should recognize that this is true, and every character seems to be a different dimension secluded from each other, and the only way they prove their own reality and existence is by interacting on a superficial level with each other, which is also why they "fail" their "relationships".
Now on about the morale of this setting. There is no reason why love between a man and a woman is immoral or wrong.
The reason why a relationship is immoral or wrong would be to overstep ones boundaries and act irresponsible, for example impregnating a woman and then throw her out as if she was trash (like e.g. Karl Marx did with his maid).
If a man in his 30s or 40s dates a highschool girl and retains a pure relationship until she is of age and marries her, there is nothing immoral done.
Of course, there would be mean looks from people who don't acknowledge this because they would think that the man is sexually exploiting the girl, but if she was just just a few years older, there would suddenly be no problem anymore, even if he were to sexually exploit her and throw her away.
In reality, none cares about morals, they just want to save face in society by enforcing crappy rules that destroy the lives of men and women because they enforce irresponsible romances on both ends (teenage romances that often lead to promiscuous sexuality on women, which lowers their ability to bond as adults, and irresponsible boys who become irresponsible men because they can get love & sex without taking responsibility, and this in turn creates adults who continue to act irresponsibly, burying their chances on a happy future and a fulfilled marriage).
What is really important is the will to act responsibly towards the one you love and to yourself.
Don't sell out yourself cheaply for the fun of the moment, and don't commit to someone whom you don't want to hold dear enough to spend your lives together, that's what really is important.
Enough self-respect to commit only to a person whom you deem worthy of you and enough respect for your significant other to accept his/her commitment wholeheartedly.