I'm not going to support my partner's new job prospect
Why can't you support their new job opportunity?
I don't know anything about the new job so I don't support it
You need to be supportive of your partner and the choices that are made. Talk to your partner and learn more about the job instead of being critical or your partner will not be as understanding of your choices in the future.
I need my partner to be supportive of me as well.
That is a start on the right foot. If you need to know more about their new job, just ask them about it. I am sure they will share the details and it will solve this whole misunderstanding.