If this is the D/s model you are shooting for, could keep in mind that CHANGE along brings those transitional feelings as the "new normal" settles it. It's gonna feel weird until the "new normal" is actually "the norm around here" if that makes sense. Edge play is edge play
no matter what BDSM flavor you like best.
Maybe being aware of the general stages of grief
you might feel with the loss of "just us two" or the "loss of old GF?" Or being aware of some possible poly hell type
feelings could help? Can't list every feeling you might feel ever, but getting a handle on some common ones might make the transition easier and helpful in avoiding potential pitfalls?
I'm sure you can find more links to help.