If you want to travel overseas while your temporary partner category visa application is being considered, you will need to apply for a specific bridging visa to allow you to travel overseas and then return to Australia. To be granted such a bridging visa, you will have to provide reasons for the travel and then the travel component of the visa will be tailored accordingly.
The only problem is you are not allow buy a one-way ticket to Australia if you are holding a tourist visa. What I'm going to do is buy a cheapest ticket to Auckland (should be the cheapest) from budget airline. But if you are going to buy a return ticket, then it's alright!