De or het wellbeing?

The correct Dutch article is:

de wellbeing

Rule Words ending in -ing: almost always de. See the rule
Meaning (Dutch) een complete toestand van fysieke, mentale en sociale gezondheid, en is meer dan alleen de afwezigheid van ziekte.

How to use wellbeing

the wellbeingde wellbeing
this wellbeingdeze wellbeing
that wellbeingdie wellbeing
our wellbeingonze wellbeing
your wellbeingjouw wellbeing
every wellbeingelke wellbeing
which wellbeing?welke wellbeing?
a big wellbeing / the big wellbeingeen grote wellbeing, de grote wellbeing

Meaning, plural, diminutive, pronunciation and translations: WikiWoordenboek (Dutch Wiktionary) (CC BY-SA 4.0). Example sentences: Tatoeba (CC BY 2.0 FR).