(rare) Alternative spelling of 猿も木から落ちる

perfectionism

a tree; more specifically, a living tree / the bent and gnarled trunk or roots of an old tree / wood, lumber / something made of wood / in ancient China, a wooden musical instrument

person

perfect, infallible, complete

perfection, infallibility, completeness

to forget / (auxiliary verb, after the continuative form of a verb) to forget to …

猿, 猻: a monkey

even experts occasionally make mistakes: even Homer nods, a horse may stumble though he has four legs

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend