I dont see any IL recognition of common law marriage, nor any state mandated treatment of domestic partners (health insurance mandate being the big one). Domestic partnership likely requires a piece of paper anyway, so why not just get married?
The quantifiable benefits of marriage in the US typically weigh heavily in favor of marriage. The systems are historically set up this way. $100k difference in income means about 3-4k saved in federal income tax, and more as the upper earning goes up. Not to mention stepped up basis, health care coverage, health care benefits (visitation) and even the spousal privilege in criminal law.
I agree its a personal decision and preference and it DEFINITELY doesn't define the relationship between two people. However 9/10 times its a financial no brainer and anyone who says otherwise is talking out their ass.
FWIW I fall in the 1/10 where marriage doesn't make financial sense (a paper divorce would save us 7-10k/yr and most the other stuff we have in place with legal agreements) and yet im still married. So im just as financially irrational just in the other direction.
