Moving from long-time school/instructor?
So for context: I'm 17, and once a week for the past 4-ish years, I've ridden at an English trekking centre near me (aside from a year out, some of which I fostered a rescue horse). The centre, which also focuses on therapeutic riding, is a very small, relaxed atmosphere, where I got on well with my instructor and horses, one of which was, so far, my all-time favourite horse I've had the pleasure to know in my life. Since it's a casual hacking yard, I haven't really progressed in my skills. I can walk and trot alright, but I'm very poor at cantering, my general skills are very unrefined, and I've jumped three times in total. I've always wished I could learn to ride properly, but I really loved this centre and it holds so many of my teenage memories. I'm also a very shy and nervous rider, and the two other centres that I could have chosen from are much bigger and more intense.
Due to lockdown easing up in my country, I started going back to the yard for the first time since March- for non-ridden activities only (grooming, hand-walking, liberty etc.) On the second/most recent session, my instructor told me that she had sold off half of her horses (including my favourite) and was now going to change her business completely to non-ridden, therapeutic services. She told me that if I wish to ride every now and again, I can ride one of the other horses I used to ride (second favourite horse). Now, I do enjoy working on the ground with horses, but I feel like doing so in a planned session takes the fun out of it, and when I've only got one hour a week to spend with horses, I'd rather spend my money and time on riding.
The thing is, I don't think my instructor realizes that I wish to continue with my riding, at a level she no longer caters for. I appreciate that she offered occasional rides, but doing so just a handful of times a year just won't do it for me, and I have honestly really wanted to progress properly for a while now, and learn to canter properly and jump. The thing holding me back from pursuing this was the idea of leaving everything I loved about my current centre, and with said circumstances changing I'm wondering if it's a sign. Is it selfish of me to think this? If I had hours every day and the money to do so, of course I'd love to ride at another stable and continue groundwork lessons with my current instructor at the same time, but I realize that with my current situation, if I want to learn to be a good rider, I'm going to have to change to a different yard. I'm happy that my instructor is following her dream, but if I want to really follow mine I have to go.
I just don't know how to tell my instructor this. Perhaps I can suggest that during school holidays I can take an occasional lesson with her, because I don't want to lose contact and such, but I don't know if this will offend her? She's told me that she expects her client base to change, but I'm one of her longest regular clients, and since I'm such a nervous rider she probably assumed this change would actually suit me better. If anyone here has had a somewhat similar experience, or is an instructor themselves, please let me know how I should go about this!
TLDR; How should I tell my long-time instructor that I need to quit lessons with her due to her changing her business from riding to non-ridden activities without causing conflict or offense to her?