Hi Susan,
I like a good ghazal and I like this one. It works a lot of varied ideas and images into its theme. I have a few suggestions/questions.
In the first couplet (I know there’s a fancier word but I’m going to stick with couplet) the two options, anger and bitterness, feel more or less synonymous to me, yet the “Or” makes them sound like contrasting ideas. Could “And” work instead?
In the third couplet, and this may be a very picky point, the phrase you use “Be kind. Rewind” was famously always used in video rental shops to remind people to rewind their VHS movies before returning them. It doesn’t really fit with mixtapes, to me, which one could just press “play” on and enjoy at any point. Obviously, I understand how you are using it but the 1980s teenager in me drew back a little. Could you get away with, “Our friendship’s VHS played to the end” or “Our buddy movie played out to its end” or some such thing?
In couplet five I didn’t understand “tangled tau” until Googling told me that “tau” is a protein that has some influence on Alzheimer’s disease. I wondered if this was a somewhat obscure reference to make the point. Maybe it’s just my lack of medical know-how.
Finally, by the last two couplets the speaker seems to have resigned themselves to the loss of the friend. Yet the poem ends on a question, which suggests that in fact the haven’t resigned themselves to it after all. I understand that this is probably deliberate but I wondered if it might be more powerful to stick with the resignation, like this:
Whatever ensues, this is where I get off.
I'll never know if I maligned your heart.
Finally, “Dissolve the pearl in Riesling. I've resigned your heart” seems to have 6 beats. It doesn’t particularly bother me but it might bother you.
Mark