One of my very few certainties concerning tarot to this day has been that, no matter whether it can or can’t foretell the future, whenever Death or the World come up, eg in a relationship reading, it signals the unnegotiable, final word on that question, and from there, there is no going backwards-nor forward.
Shouldn't you be asking the cards if this can be changed? I mean, you are, in part, correct about the Death card. As tarotbear says, all things must come to an end and the Death card usually indicates that: The End for this, no bringing it back from the dead like a zombie (who'd want that?). BUT getting the Death card in a reading doesn't always mean "IT WILL DIE!" It often means that something, like a relationship,
may die if we don't do anything different.
I, myself, never take it as a given that the Death card or World card or combo of both indicate a guaranteed end. I always ask the cards if something can be done. And most of the time, I've gotten positive answers that, if acted on, have changed things. They don't bring the dead back to life, but like CPR, they stop the relationship from dying and give it more life.
Which is all to say, however convinced you are that these cards mean a non-negotiable end, neither you, nor we, can know for sure that these cards indicate that. Only the cards know. So why not ask them if there's a way to prevent this end? They might tell you "Sorry, time's up for this relationship. It's over." But there's a chance they may also say (as they often do in my experience): "New life can be breathed back into this dying relationship if you just do X..."
I wonder, however, if there might not be a more important question: do you want to save the relationship? Is it worth saving? Perhaps the Death/World card together, which always indicates a final end to you, appear because you want it over, and so are planning on letting it end. Self-fulling prophecy as it were.