my uncle and aunt both passed away last week :(

Sorry for your loss, but it not for us to ask why. It's the Lords plan, as sad as it is to loose loved ones.

sorry to hear of your loss

Aside from accidents that kill people together...

Sometmes when married couples die close together, one right after the other, is because their biocycles are in sync.
For two people that are in love with each other, lived the majority of their lives together, dying in quick succession of each other is thought to be the the ultimate romantic expression.
Its also common for a dog to die soon after their loving owner passes.

With so little information on the conditions it is impossible for anyone to make any assumptions for the reason it happened to your family.

To me, it makes me think that their love was so strong for each other that the loss of one was unbearable. When people get up in age life is a struggle. To have the courage and conviction to just "Let Go" is a form of ultimate dedication and commitment with the one you love.

It doesn't even need to have religious implications but often times it does...
...To meet up with their love in Heaven
...To follow their love to heaven
...The next step in their journey together

Or...It might be purely selfish...
...Can't go on without them
...Nothing left to live for
...Had a wonderful life but now its time to go

I believe I read somewhere that heartbreak can kill you.
Especially if your heart is not as healthy as it should be.
I've felt the pain of stress, sadness and misery.
It taxes the heart and degrades health overall.
If you are already weak from age, it could push you over the edge.

Try not to be sad for them. Celebrate your memory of them instead.