YA Fantasy Saga about a group of 7 friends (?) with powers and i think they could travel to another world one of them was called Diana

[Paula]

I read this book in the early 2010s and it didn't look modern by then. The book's cover was framed in orange with an illustration in the middle and the author had an englsih name (could've been american). I don't remember much about the plot other than:
SPOILERS AHEAD
Towards the end of the book, one boy realized he loved this girl called Diana but he sensed some kind of danger and so he shot an arrow and it turned out that the danger was the girl he loved and he had killed her
And then the main character who was a boy (I think the name might have been Mat?) said he "closed his eyes for longer than a blink" or something like that and he took the boy out of the crime scene

[Bonnie]

This series has a Diana and a Matthew that time travel. I haven't read it.

A Discovery of Witches

[Paula]

Bonnie wrote: "This series has a Diana and a Matthew that time travel. I haven't read it.

A Discovery of Witches"

Hi! just checked it and it isn't it
Thank you!!