One of the most important issues is to maintain access to the kinds of food your Thai partner is used to eating. It is a big issue but they may not verbalize it to you. Food has a very significant impact on our general demeanor and day to day happiness. The majority of travelers experience this themselves when overseas on vacation. By the time they get back to their home country they are really hanging out for their regular diet. Funnily I have found that I prefer the Thai food better than my previous diet. For Thai people, preparation and sharing food has a great cultural significance. They also find a lot of western food tasteless and or overcooked. A lot of Thais do not eat Beef. From what I can work out this is not a religious issue as it is for Hindu people, it is an issue of respect. Predominantly Thai women are small breasted and often don't produce enough milk to wean their children. Cows milk is used to fill that shortfall. They respect the animal that sustained their lives after birth and prefers not to eat it.
That said you should understand your partner is not here just for a vacation. She will not be happy to wait till she visits home again to taste Thai (real) food. But hey there is no problem because there are plenty of good places in Perth and the suburbs to get everything she needs. You just need a starting point.
Thai Restaurants: there are many good Thai restaurants in Perth because it is so popular. You will have to try a few because some westernize their recipes till they hardly resemble what you partner expects. There are many that still offer traditional Thai food. Be aware the Thai food does vary throughout Thailand also. If your lady is from Nakhon Ratchasima she will enjoy dishes that may be best described as Thai/ Lao. If she is from Udon it may vary again. If she is from Bankok or Chang Mai or Chang Rai again her taste may vary. Find one that suits her. Her Thai networking will probably find what she is looking for.
But you can't eat at restaurants all the time, and she won't want to. She will get a great deal of pleasure just cooking the meals she likes. So shopping for the groceries she needs to cook at home will be your next challenge. There are quite a few places in Perth and suburbs to do this. In Northbridge there are three maybe four good places that sell a wide variety of Asian groceries. A lot of this is the product of Thailand.
If you are further north of the river there is a very good Asian supermarket in Glendalough.
Heading south of the river there is Kong's on Albany Hwy going towards Cannington.
You should be able to pick up Chilli plants, Lemon Grass, Coriander etc at many nurseries and a number of the other regular herbs as well. Some of the more obscure plants you will get from friends of friends through her networking. When I say obscure I mean I can't spell their names as my lady pronounces them....haha. But you will find them.
You may find she is not impressed with a lot of the cuts of meat (pork especially) in the supermarkets. You might balk at the price of what she spies in your local butcher. There are two good Butcher shops in Northbridge where she will get exactly what she wants at a price you won't believe. They are very cheap. My favorite is the Chinese butcher in Northbridge - opposite 'Kai Phu Thai' which is the best place to get all her Thai DVD'S at a few dollars each. So you can kill two birds with one stone because they are directly across the street from each other.