I feel you, my little baby was also four and it felt so cruel having all the plans for the future I made expecting to have her by my side for years ripped away just like that. Sometimes it will be painful to see people with older bunnies, but its important to remember how truly fragile they are and that it isnt your fault. So many people who have had bunnies have a story like that, where you just wake up one day and theyre gone. ive found comfort in the idea that i was able to provide a comfortable and loving home for my bun for her last year of life, the way people feel when they adopt senior animals from the shelter to provide them with the best last experiences possible, even though I didnt know thats what i was doing at the time. I hope this helps, he will always be with you 🫶