IndianRingNeck.com

I have a female IRN, she has been spending time in her nest box an awful lot, comes out of it but not more then 20 minutes and goes back in for hours, the Male Irn sometimes goes in when she isn't in there during the day and goes in at night, I dont see any eggs, what would the bird be doing in there?

Depending on your location, is it coming into breeding season?
You hen maybe getting the nest ready for when she does lay eggs.
My hens seem to spend a few weeks getting the nest 'just right' before laying. Perhaps that is what your girl is doing also.

Do you know when breeding season is in Michigan?

breeding season in the US is just about started some friends already have eggs

In upstate New York, probably the same latitude as Michigan, my 2 lutinos have been courting for the last 2 weeks, starting about Feb 1. He has not yet mounted her; but she begs for it, and he has been getting closer each day.