This is a tricky one.
I haven't been in this situation myself but I can perhaps give you a woman's perspective.
She wants to be your everything. Your world, your light and your love. Knowing that all things considered, you will put HER and HER wellbeing even before your own and the A indicates you put your own wellbeing ahead of hers.
So, maybe she know's you loved her but at the end of the day you loved yourself more and tended to YOUR own needs more than hers.
This is how I as a woman would see it. It would be very hard for me to understand the "compartment" argument. With that said, my AP made it very clear he "loved" his wife. I know he did. I know he loved me too but nowhere near in the same way. I know my AP didnt start the A cos he didn't love her enough. It was all the claasic reasons of ego stroking etc.
He demonstrated his love for his w in ways he could manage (not talking about her to me)
In my case, I would probably say what your BS is saying applies. I probably didn't love my H enough. I loved him - but not enough to withstand his emotional unavailabilty and tolerate it.
Does loving someone enough mean tolerating their deficiencies and continuing despite this?