I think many of us have had some regain in one form or another. For ALL of us, once the surgery stops working it's completely up to us.
Post op 7 years next week, when I was losing I thought I was invincible and had no fear of regain. But I lost a parent, changed jobs, changed jobs again, went to night shift, went to grad school, dealt with all kinds of things, and the 'eat all things in small amounts' went out the window.
I had to fully commit to a very specific PERMANENT very low carb lifestyle. I lost all my regain and more, but I have eaten only a ketogenic level lifestyle for the last 6 years. I am not one of those patients who loses their weight and can resume eating all things just in tiny amounts. I have to work at staying very low carb, no sugar, almost no fruit, no starchy veg, no bread/rice/pasta/oats/grains etc. I basically eat meat, green veg, eggs, cream/butter, and a high protein shake with water or almond milk daily. it's a tight regimen but it works for me.
Remember your WHY. find it and recommit. you totally got this!