Given the amount of time, I would ask for a minimum of a year before making that decision. Moving into a marriage after a month is romantic, but not reasonable, and making someone a co-founder after a month is not reasonable. (In my opinion.) At a month, they may not have even had their first fight. You've been at this for more than 3 years, and this person is interested in a stake after 1 month?

Another way to look at this involvement: Imagine you hired a consultant do some work for you and they made significant contributions, connected you with some companies, and formed some partnership. Does that person merit the same benefit?

If the issue is pushed further, I'd strongly recommend talking to a lawyer privately. And make sure that lawyer represents your interests and the company's interests.