Common Law Marriage in Indiana?

No such thing for Indiana.

IC 31-11-8-5
Common law marriages entered into after January 1, 1958
Sec. 5. A marriage is void if the marriage is a common law marriage that was
entered into after January 1, 1958.
As added by P.L.1-1997, SEC.3.

If I had a bit more time to indulge my historical curiosity, I think I would go looking for two cases: Stoner v. Howard Sober, Inc., , 128 Ind.App. 371 149 N.E.2d 121 (1958) and In re Sutherland's Estate, 246 Ind. 234, 204 N.E.2d 520 (1965).

No, my point today comes from reading ‘Common law marriage’ - a myth from The Harrison Drury Blog. I think this paragraph applies to Hoosiers as well as to the English:

Despite this, over 50% of people still falsely believe that cohabitants are
protected by “common law marriage”. The concept does not exist.

Maybe even more so for Hoosiers, since the British appear to be taking action to protect those living together.

The writer gives their top five tips and all are very good (and easily applicable over here in Indiana), but I like this one best as it contains a universe of good advice:

If you have any doubts about your legal position, take legal
advice to protect yourself, your partner and the children