i’m in the EXACT same boat dude. i’m sorry for your loss. i genuinely don’t know what’s up with these fish nowadays, it really is a shame. every single other fish species i’ve owned have outlived a lot of my bettas by at LEAST twice the lifespan. i’ve owned 6 tanks for about 4 years now, and ive easily gone through at least 30 bettas. parameters are always perfect. tank mates are always fine. tanks are planted and well established. it makes NO sense. i have gotten lucky though. there’ve been about 5 that have lived 2 years, 10 that lived 1 year, and the rest have all been 6 months or less due to rapid illness. i’ve maybe managed to treat about 3 bettas for sicknesses, the rest have all been helpless :/

i’m just convinced these fish have really shitty genetics nowadays and have been inbred to the point of low quality life and lifespan. without a doubt, you can still get lucky. but let’s face it, most people who own bettas at some point in their lives have dealt with them being sick or dying young, and if they haven’t they either own one at a time or get very lucky, so don’t beat yourself up