If I recall correctly, Rosellas should not be bred until they are around 2 years old, and can lay fertile eggs until they are around 10 years old. That's the general breeding timeline for them.
That being said, it doesn't at all sound like you're going to get any fertile eggs. As you stated that "They don't show any interest in each other at all", unfortunately that means that the male you brought home is either not interested in her, or she is not interested in him, or neither is interested in the other. Parrots are very much like humans when it comes to this situation, they must FIRST bond with a bird of the opposite sex and become very closely bonded to that bird BEFORE they even think about actually mating. Only after they become closely bonded with each other will they start to exhibit breeding behaviors towards each other, which will eventually result in mating. It's not like breeding dogs, cats, rodents, etc., where a brand new male can be put with any female that is in-heat and they just mate on the spot. Birds must actually like each other, be attracted to each other, and become quite close to each other before the act of mating will ever take place. So unfortunately, if you bought that male Rosella specifically for the purpose of breeding with your prior female, and they've been together already for a year and still show no interest in each other at all, it's probably not ever going to happen, and definitely not going to happen any time soon, as they are not yet even bonded with each other, or even showing interest in each other. So there's no chance that they will mate any time soon.
This doesn't mean that she won't continue to lay infertile eggs, so you need to always make sure that she has access to a mineral block and a cuttlebone, and that you're feeding her a nutritious, varied diet that will keep her from becoming malnourished while egg-laying, or much worse, egg-bound.
As it was already mentioned, you also need to watch these two very carefully since they are not bonding and are not showing interest in each other at all after a year, as this may mean that they'll just simply exist together in the aviary and avoid each other, OR it could possibly turn into a volatile situation where they start to harm each other. So if you see ANY SIGNS OF PHYSICAL ABUSE from either of them towards the other, then you need to separate them ASAP. Hopefully this won't happen, but you never know.
You may also want to buy some fake eggs at a bird store, or order them online if you can't find them, and start replacing the infertile, real eggs with them as soon as she lays them. This way she will lose interest quickly after she realizes they aren't going to hatch, and once she stops laying on them you can remove the fake eggs. This should help to stop her from constantly laying infertile eggs, which is not healthy at any age.