If you can, have them next to each other where they can see and smell each other from their own hutch/cage.
Introduce them in a neutral space and make sure you have a few hours time to keep an eye on them (but don't interfere).
Depending on how much of a testosterone rush Ernie is suffering from, expect anything from a lot of rumblestrutting, bum-sniffing, chasing, humping (not necessarily from the right end). The lady will answer with a LOT of high pitch squealing, squeaking, whimpering and running (but never far!), trying to protect her rear if she is not in season and ready to mate. she may kick out at your boy to tell him off.
He will pee at her to show her that she is HIS chosen mate, she will squirt back to tell him literally to p*** off. It can get RATHER smelly, as the male pee is loaded with testosterone.
The intensity can vary a lot, as can the time it takes them to settle, from a few hours before they curl up together to several days, when a boar goes totally overboard and has this brain turned off completely - not a pretty sight, I can tell you! I have one of those boars...
Expect a smaller version when the lady comes into season for the first time; and very occasionally a flare-up of testosterone in the boy.
A bonded couple is usually quite devoted to each other; and your Ernie will be a very happy boy!
I am very sorry that you lost your Bert. We have a Rainbow Bridge pet section where we remember our lost ones and share our grief.
Please keep us updated! I'm looking forward to pictures of the happy couple!