Where does “nonhappening” come from?

nonhappening (English) comes from English non, from French non, from Old French non, from Latin nōn, from Old Latin noenum, from Proto-Indo-European óynos — one; single.

nonhappening (English): failure to occur; something that does not happen;...

Definitions

failure to occur; something that does not happen;...

Ancestry of “nonhappening”, step by step

nonhappening traces back through two separate lines of ancestry.

via English non

Step	Language	Word	Meaning
1	English	non	Obsolete form of none
2	French	non	no; not; a no, a negative response
3	Old French	non	no; not; Alternative form of nom
4	Latin	nōn	not
5	Old Latin	noenum	—
6	Proto-Indo-European	óynos	one; single

via English happening

Step	Language	Word	Meaning
1	English	happening	present participle of happen; Busy, lively;...
2	Middle English	happenyng	—

Every word from Proto-Indo-European óynos →Every word from Old Latin noenum →Every word from Latin nōn →