I want to go vegetarian when me and my so move in together
That's pretty good. Why do you have to wait to move in with them first?
We don't disagree with me on the issue and we help each other on decision making, so it will be easier to do together.
I think it's great that you want to make healthy lifestyle choices together. Changing your diet can be difficult, so doing it together with your partner can really help to keep your going on the right track. You can start without your partner if you want, though.
That's not how we are.
That's completely reasonable, too. I'm glad you're with someone who wants to live a healthy life together with you.