They never Bonded.
Between the war and their species, it was never the right time.
After the death of Optimus Prime, Primus himself had given her a gift. Now it mattered not that she bled, for now when she did, it was energon, same as him.
They never Bonded.
But Tera still felt the pain through all her circuits when Sentinel Prime shot through her mate's chest the first time. And she'd be damned by all Gods if she let another befall Ironhide.