Übersetzung - Η αγάπη είναι καθυστερημένη. (Griechisch)

Yup: all joking aside, there's no meaning of "late" in this text at all for me either.
I don't think we'd ever use "retarded" this way to mean "late":
"The train has been retarded"
would mean "made late" or "become late" but first, it's quite a rare way of saying "The train is running late." And second, I can't think of an example where we would ever say
is + "retarded" to mean "late" (as a state).
After all, Love is Dumb. That's it, that's all...
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Live, Love, Learn, Laugh...

Both "retarded development" and "retarded growth" use retarded in the sense of delayed or late. In the US when referring to a child's mental capacity the term "retarded" is now discouraged and one of the more politically correct terms is "delayed".

Hmm...
Out of context, in the dictionary, I certainly agree that retarded can indeed mean "delayed" or "late." But I couldn't say
He is retarded
and mean
His growth has been delayed
could you?

I certainly would never use that expression myself (except as a very obvious joke which is what I think this text is, or maybe a sigh or something...), because I definitely agree that we should avoid such potential terms of abuse.
But we're really getting off the track from the point of this text here in front of us to be translated?