Hi VocaFan62! And welcome to the boards!
I am really sorry that you feel this way and I would like you to know that you are not alone. Our libidos are taking many hits from the pandemic, different economic situations, sickness, mental health issues, stress, medication, and so on. However our libidos change throughout our lives for many reasons so it is expectable that we will have at some point this kind of differences with our partners.
It's great that your boyfriend is reassuring you that he understands. However, him suggesting sexual stuff often could be creating a lot of anxiety on your end; something that can outright kill your libido. How about taking some pressure off the topic and try just going with YOUR flow? Maybe you could ask him to stop suggesting for a while so you could take the initiative whenever you feel like; without deadlines. Maybe approaching intimacy from a different perspective could help you both rediscover something that works for you two.
Since you mentioned it, I will link an article about intimacy that is one of my absolute Scarleteen favorites:Intimacy: The Whys, Hows, How-Nots, and So-Nots
It was life changing to me when I discovered that intimacy with a partner could mean such a wide array of things.
I would also like you to know that myself am no stranger to the guilt of not wanting to have sex with a partner. Especially as women, we are socialized to feel responsible for the satisfaction of the people we love. So it is natural that no matter how understanding he may be, you still feel like you are failing him. I have no magical solution for this because it's deeply embedded into our social beings. Although, recognising this pattern is a great place to start.What you want and feel is just as important as what your boyfriend wants and feels. You have every right to not want sex at any time, and you shouldn't feel guilty for that.
I have the feeling you already know this. However, it's important that you hear it/read it until it sticks, you know?
If you depend on these medications it is possible that you will be able to sort some of it out, and it is also possible that you will have to learn to live with this to some extent. I will link an article that could be helpful with the latter: Sexual Negotiation for the Long Haul
Do you think some of this makes sense? Does it resonate with you? Please let me know