I am a lesbian and have been involved with my partner now for almost two years. She has came out to everyone but her parents, even her 9 year old daughter. Everyone has been so accepting. The dilema is that I can not be her partner when we visit her parents for holiday events or birthdays. I have to shift gears and become her gay friend. This puts and extreme amount of stress on me to become something I am not and from a moral perspective I feel like her parents are being deceived since they think the world of me. She keeps putting the conversation off until something comes up and she is forced to deal with it. I have been more than supportive and patience but I just do not want to pretend to be her gay friend we are suppose to be in love and plan on buying a house together within the coming year. She has a beautiful engagement ring that I gave her but it comes off when its time to be around the parents. When is enough enough? I have even questioned her sexuality since she went from being bi to lesbian... Maybe I am over analyzing.

Sometimes people have to be honest.it is her life and even if her parents disagree with her being with you it will still be her life to live. What I am saying is she does not need their acceptance to be who she is, if they don't accept you as the one their daughter is in love with then that's too bad for them.
To me it shouldn't matter if you are gay, lesbian, bisexual, if I was engaged and my pertner took his ring off around other people I would ask for it back as he obviously didn't want it in the first place, you guys are either engaged or you are not.
Sit your partner down and have an open honest talk with her, let her know how this is making you feel, seriously after 2 years with you she should be able to tell her parents about you.. good luck

I don't know if there is a right answer to this so throw this out if you don't like it but I kind of think this has to be her decision when to tell her parents and not be forced on her.

I also wonder if her parents already know, if the 9 year knows, I would imagine that she has said something at some point as most 9 year olds don't hold secrets very well. Even if she never said anything, the fact that you come to holiday functions and are moving in together leads me to believe that they have an idea.

The way she handles her parents, is her business and not yours. I understand your feelings, but you must respect hers. Don't make a big deal of this, as its only for a limited time, and for a limited audience. Until she is ready, do nothing, and do not put the pressure on her either. Maybe you don't care about how her parents feel, but she does so, let her handle it her way, or stay home.