I literally cannot remember this series but i know it involves wolves and a triad but one of the mates is killed. He gives his shifting ability to his non shifting mate in one of the books but later on in the series the dead mate is resurrected somehow.

[Miss A]

If it's multiple triads throughout, maybe Tri-omega Mates by Stormy Glenn, or something by Lee/Lisa Oliver or Lynn Hagen.
I will keep looking.

It sounds like Triad series by Poppy Dennison. She also has the same series on Amazon under her other name Macy Blake i believe is her name but you can also read them from other name.