Where does “-inge” come from?

-inge (Old Frisian) comes from Proto-Germanic -ungō — -ing, -ion. "Forms gerund nouns from verbs.".

Ancestry of “-inge”, step by step

Step	Language	Word	Meaning
1	Proto-Germanic	-ungō	-ing, -ion. "Forms gerund nouns from verbs."

-inge — Etymology, Origin & Word History | Etymology Explorer