So far you have handled this very well. You are giving her space to work this out in their own time. If you rush things you may find that they are more resistant than if you allow things to play out. Taboos are very powerful and she needs to work out how to tell them and how to include you. Since these are her parents, she needs to decide on her strategy. She will decide on how to tell them. I know it is asking for a lot but you have to let her handle this situation. You are feeling this way because you want this relationship but you have to let it play out. She has made a commitment so don't let impatience ruin it. You will look like a very understanding partner if you work with her on guiding this process. When she feels ready she will let you know. You have to trust your partner.