I’ve seen it too many times – someone separates from their spouse, but never gets divorced and never does a separation agreement because they don’t have kids and “it doesn’t matter”. Except, it does matter.
If you are legally married with no separation agreement, your spouse will inherit your entire estate if you don’t have a will. If you want this to happen, then go ahead; do nothing. But this is probably not what you want.
Of all of the clients I’ve had come to my office, bewildered at their sudden inheritance, I’m quite certain that none of them expected to inherit, and I’m also quite certain that their former spouses did not want them to inherit. Further, I’m quite certain that their former spouse did not want them arranging their funeral and burial, but that’s also what legally happens.
Don’t assume you know the law. Don’t assume that what you want to happen, will. If you are no longer with your spouse, get divorced, or get a will. Better yet, get both.