Never been married. Never want to get married (long story... won't bore anyone with it), so I'm going into this thread with an obvious bias...
As mentioned in a previous reply, a prenup, drafted by your attorney, and reviewed and approved by her attorney is absolutely required to protect you and her
Beyond that, I will only suggest you thoughtfully consider the following question before you drop several thousand on a rock:
What can you do while married that you cannot do while still single?
Have kids?
Share funds for common expenses?
Travel?
Co-own property, cars, other expensive assists?
Have sex?
Medically/psychologically incapacitated care, or post-death estate executor/management?
Family events?
Share health insurance coverage?
What else?
I submit that all of these can be done without being married, though you may need to draw up legal docs like a power of attorney or living trusts to ensure each of you have the rights and powers you agree to have.
Can you do everything and anything you want to do together without being married? If yes, why get married and potentially obligate yourself to perpetual monetary support if (after) you split up?
Not a comfortable discussion, I know. But your trusted professional service providers (lawyer, tax expert, doctor, investment manager, etc.) can give you an unbiased review of what you get and lose from marriage within their area of expertise. You really want to have those discussions before you stand at the altar.
Life is good
The Cat