I'm sorry about your fish
I've had bettas that didn't live long - my theory is that they are so over-bred and kept in such appalling circumstances in the LFS that their health is permenantly damaged. Many experienced fish-keepers say that 18 months is their typical lifespan, even though it's a lot longer in the wild.
So before you give up fish-keeping altogether, why not consider keeping something a little tougher instead? As you know, my bristlenosed plec seems pretty well unkillable (Brillo, who rose from the dead). My black neon tetras could survive a nuclear bomb, I reckon and my sailfin mollies are also pretty hardy (not lyretails or fancy mollies, however). I've had a lot of success too with pearl gouramis, who are like bettas in personality but lack the easily damaged finnage. But top of the list of unkillable are danios.
Provided your tank is cycled and everything is working there is no reason why you can't keep the same fish for years and maybe something hardier would give you the chance to develop experience without the upset of losing fish? Avoid something very popular or very fancy and far removed from the wild type - mutts are generally a lot healthier. And start small - a few hardy fish that can help you develop your confidence.
I just feel this would be a sad way to end a hobby and I am a firm believer in not giving up just because something turns out to be tougher than you thought. But at least you gave that fish a good life, even if it was prematurely ended.
