You need to repost this question in the immigration section of avvo. Best of luck to you both.
Legal disclaimer: Ms. Braaten's answer to your question does not establish an attorney client relationship, but rather is meant to share knowledge with the general public. For specific advise on your case, you need to consult one on one with an family law attorney.
Are you asking for an alternative to getting married?!
Please be advised that any answers or information disseminated above do not constitute legal advice and that the attorney responsible for this posting is merely attempting to participate in a Q & A session intended to be helpful but certainly not intended to be legal advice. It is important that you understand that no attorney-client relationship has been formed and that the attorney has no obligation to follow up with you with your legal issue unless you separately contact said attorney and arrange for him to legally represent you.
Live here for the 90 days and then go to the UK. You might be able to extend that 90 days if you get engaged, but would have to talk to an immigration attorney about this.
R. Jason de Groot, Esq.,