it's a popular book, and one I've shared with my son and other children...I saw it as an inter-generational thing, illustrating that the people who once take care of us sometimes become later themselves helpless and dependent on our care in turn...
Because of the strangeness of grandparent behaviour in our families I have always tried to find things which to me portray a more 'normal' depiction of unconditional love and emotions. It took years for my childrens' grandparents to want any kind of contact- the slightest thing would send any of them into a huff or a rage, I realise now they couldn't handle anything they saw as a rejection, eg. a child refusing to hug on demand, or having a tantrum, or misbehaving.
But I can see why some people who never felt that care in the first place might be spooked by the book, especially anyone who has had abuse which was sexual or involved inappropriate intrusive behaviours.
I don't think it was written to be that way, but I can't know whether it was sent to you with the intention to upset you.
Only you know what other people on the outside of your family may never have seen or see.
The fact it has upset you and given you questions is something you can work through though, and especially accept that these are your feelings, and valid.
Many things upset me or make me cry, touching on a particular nerve.
I've learned that I can't always explain them fully even to my closest people, for a long time I took them to the therapist;
you can always bring them here.
The hardest thing for me in "love you forever' was the knowledge that not only my parents couldn't possibly do that- but their parents, my childrens' grandparents, and now even my siblings cannot feel a love which puts their babies or anyone before themselves.
I don't expect anyone to take care of me unconditionally when I'm old- but if the kids I influence can love and want to if it were possible ( which it isn't of course ) then that's the hidden message for me, and something which has been missing in my family for a long time. I hope it helps them realise that love is not a control mechanism, or a trap, but that we can love and still have to let go, except in our ideals and our hearts.