HiCustomer Thank you for asking your question on JustAnswer.
It's better that she is honest with you than to have waited until you were married for a year and tell you she made a mistake. With thaqt being said my suggestion to you is to give her some times but also reserve yourself to the fact that she may be having second thoughts about the relationship but you don't know for sure so give her some time to figure things out. You're right about not pushing her because that would surely push her further away from you and since you love her that is something you don't want to do. I think you should try to find out if that phrase isn't because she has someone else in mind or has meant someone else. That is usually when a person says this but it may be different in her case. Ask her if she cheated on you with someone else or has someone in mind to be with it just seems strange for her to say that after being clearly happy about getting engaged there has to be more to her story than just having cold feet or not being "in love" with you anymore.There has to be some underlying reason why she goes from loving you and wanting to spend the rest of her life with you to not being "in love" with you anymore but loving you.
Thank you again for trusting us with your problem.
Definitely ask her in person so that you can see her facial expression and true reaction to your questions and if she has nothing to hide then she shouldn't get mad try asking her this way, " I really hope that I am wrong but because your comment came out of the blue to me then I need to ask you this, did you cheat on me or are you planning to cheat on me or break up with me for someone else?" Explain to her that you don't go from loving someone and planning on spending the rest of your life with them and then turn around and say that you love me but not in live with me anymore. If you write an email and ask her that gives her time to think of a lie or be deceiving.