"I will always love you, no matter what."

[WarVick]

Why is 'egal was passiert' not acceptable here?

[ArmasUkkoM]

"egal was kommt" is I'd say a little bit more common, but "egal was passiert." is equally correct.

[Menschenkind]

I agree. Another solution, not as literal but also quite common, maybe a little more formal: "komme, was wolle" (come what may).