I have really no idea at all what you are talking about.
Except...
I think you have a really rigid idea of what marriage is. I bet you are a person with quite rigid ideas of what is 'right' and what is 'wrong'. I'd bet you have a very strict definition of marriage, and even stricter ideas of how you 'should' feel about getting married.
Would it help at all to remember that for thousands of years, 'marriage' is exactly what you have. A partnership, and even more so, a partnership that exists to raise children. Marriage is a relationship that is nothing to do with a ceremony, a big dress, a party etc - it is waking up every day with a man that you don't want to leave right this minute. It is a living partnership between two people who accept each other as normal, fallible human beings with flaws, often big flaws, but despite those flaw, you agree to keep living together, to live together for the foreseeable future, and to raise children if they come along.
That IS what marriage is. If you got married thinking, I want to live with this man. I want to raise my child with this man. I have no plans or desire to split up with this man, then you did NOT lie. This is what marriage is. Don't believe the Hello/Mills & Boon lie about eternal physical/spiritual passion, about the big performance, the big diamond, the big dress. That's all rubbish. Trash. Marriage is a small, intimate thing. It's about the commitment you make every day of your life by waking up next to this man and sharing your life and your child with him. There is nothing more intimate, nothing more honest. In history people got married for dynasty, for money, to escape their parents, for sex, religion, for family, for freedom, fto escape social stigma, to have a legitimate baby, for love. There is NO single reason, not single true reason. Why do people get married? Even today pretty much for all those reasons, plus tradition, practical and legal reasons. All are valid. I got married as I was pretty old and I like the idea of marking this relationship as different because it was the one I would have children in with someone I trusted enough to have children with. It doesn't mean I felt a different sort of love, or was more in love than with any previous boyfriend.
Marriage truly is, more than anything else you do, what you make it.
I honestly think you need some counselling and you can do it alone. I'd recommend cognitive behavioural therapy, as it seem your preconceived ideas of what marriage 'should' be is hurting you. IMO, if you start using the word 'should' about anything at all, then the roots of that 'should' needs unpicking.