Would putting someone on your insurance, as a spouse- (by common law); but then finding out common law isn't recognized as being legal; be considered falsifying documentation?

I really don't understand this whole thing..... but I found out that common law isn't recognized as being "legal". So, I'm thinking now- I'm going to get into trouble for doing this.

Does anyone know about this kind of issue? What kind of 'trouble' might this cause? Would my "spouse" just not really be covered? Will this cause problems with my job, since I have a job sponsored health insurance?

I'm so confused and worried at the same time.