This deep psychological drama turn out to be shallow melodrama about bad parents and whiny children.
The Friendly Winter is perhaps the most melodramatic work out there. 87% of the chapters include at least one crying scene. The crying scenes aren't very short, they often take 3-5 pages of 'byyhyyy', 'mooooo-ooooom' and various sobbing sounds to stop. And usually they don't stop, some other character just starts to cry with the first crying person and then the chapter is over without anything being add to the story, to the characters nor the reading experience.
The main theme of the story is regret and letting go, except the message itself is that you will always regret and can't let go. It's not a story about developing characters or overcoming an obstacle in your life. It is a story about crying until others start crying with you and for you. If you cry everywhere, the odds that the person who is making you cry will hear you cry grow spectacularly and they might even start crying with you.
All in all Friendly Winter is pretty easy to sum up. The characters are victims and readers are supposed to care. The manga certainly doesn't try to make one care and I don't think we should.