I'm over a year sober now. I think most people would describe it as looking like it's been 'easy'. I think my dh certainly would.
Yes, most people who have a drinking problem do struggle for years to get sober, stopping and starting. For me, I did struggle for years, but it was an internal one. From the outside, I looked like just a fun person who liked a drink. Before I actually stopped, there was many years of worry about my drinking, attempts to moderate a bit better, shame about failing at it, trying to do better. I was drinking A LOT. Like 200 units a week. But I never got caught drink driving. Never lost a job. Not in debt. No failed relationships. No medical intervention. No rehab trips. When I decided to stop, I just...stopped. I knew I was ready. I was done. And I just did it.
I went on holiday when I was a month sober (with dh who still drinks) and it was fine. I went to family parties and did Christmas and village BBQs and school fundraising pub events, etc. all the things people normally drink at and I didn't drink or even think about drinking. It was 'fine'. And actually, it was mostly fine.
The not drinking is actually the easiest part about no longer drinking. He's made it through the really tricky first 3 months and that's fab. But there will be more to come and a lot of it will be below the surface. I found it has been the emotions that have come up, the stuff that I wasn't dealing with because I was drinking that I then suddenly had to deal with. But that's probably only 20% of it.
Honestly, it has made family life a lot easier. I sleep better. I feel healthier and mostly happier. Life is better. Oddly, sometimes it does feel too 'easy' and I wonder what's coming. But for some people, it does happen this way. It's called spontaneous sobriety. People just stop and get on with life.
I would definitely recommend though that he doesn't disconnect from his support network of sober people. Maybe that's AA, maybe it's something else - there are lots of options out there besides AA (I don't do AA personally). I think it can be easy to slip into thinking you've got it cracked when things are going well, which can ease into, well, it's no big deal, I'm not struggling, maybe I'll just have two beers because it's so and so's BBQ, and then it starts again. Community is critical for keeping yourself accountable and honest.
I also want to say that I think it's important that you support him in continuing to set boundaries. He went to the pub and had an AF beer and then left after 1 drink when other people were getting drunk and he felt uncomfortable. That's fantastic! That's not something to be knocked or downplayed. Lots of sober people won't even go to a pub because it's too difficult. He went, had an alcohol free drink, and then left when he was over it. That's a win.
Please don't be inviting people over and drinking in the garden if he's not comfortable with it, as someone suggested. There is a time and a place for that, but it's a decision that you both need to make together. Waving alcohol around in front of someone in their own home who is early in sobriety and seemingly doing well as a 'test' is not the way to support someone's recovery - which it sounds like you know already, but it's important to point out. It's early days. He's finding his feet and doing well. That's great. There will be tests enough in the future.