if a will is made by a couple and 1 dies is the will then void?

Usuall, when the time comes see lawyer. Personally it is best to make wills outlining what your partner will inherit and what happens if your partner predeceases you. Both of you should do this. A lawyer will advise you both

There's no such thing as a will made by a couple, the will is made by each individual. Often each of them will leave everything (or nearly everything) to the other partner. Each of them will usually specify someone else to get their property if their partner is already dead or if they die at the same time.

So partner A makes his will leaving everything to partner B, but also saying that if his partner B has died before he does then his property goes to his brother C. Partner A dies, and everything goes to partner B according to the will. She doesn't have any obligation to leave anything to A's brother C; the will of partner A has done it's job of giving all A's property to partner B, and so it's all now hers to do with what she likes.

No it's not because a will is always an individual will they may leave property to each other but there are separate wills

Not if it’s properly made out. One partner dying is the one reason to have a will.

The lawyer or person writing the will should make provisions for what happens to common assets in case one partner becomes deceased. Only a fraudulent lawyer would not do that. The couple should have made their wishes known (for what they want to happen to the assets) and then the lawyer should put that into the will.

no