Okay, so I just have to say this because I've been thinking about it non-stop for the past week since I finished Season 2. I get the hopefulness behind the "coffee theory", because it means that Aziraphale would have stayed with Crowley if he could have. But it just...doesn't make sense for Aziraphale's character honestly. Going back to Heaven to try and fix things is the only choice that makes any sense for who he is and his character arc up to this point.
We've spent the last two seasons watching Aziraphale struggle with his relationship to and love of/faith in Heaven and God. It's his entire character arc and honestly, it's the basis of who he is. Even when he may not agree with individual decisions made by Heaven and even works against those things sometimes - like, for example, saving Job's children - he still believes that heaven is ineffably good. The bad things are just anomalies or decisions made against God's will by "bad" angels.
Even by the end of Season 2, he still genuinely believes that Heaven and God are good, even if he knows that some of the things Heaven does - like Job, Armageddon, etc. - aren't good. He just thinks those things aren't actually God's will. So of course he thinks it can be fixed. Of course he'd want to try and fix it given the opportunity. If he'd run away with Crowley despite believing he had that opportunity, he would have almost immediately regretted it. Because here's the thing: going with Crowley would have made him happy, but it would have been "selfish". It would have meant prioritizing himself/his own happiness over Heaven, God, and humanity.
Of course he loves Crowley, and of course he wants to be with him and is devastated Crowley didn't go back to Heaven with him. But going back to Heaven was the only decision that made any sense for Aziraphale's character. And now he needs to figure out that Heaven can't be fixed - it's not just a few bad angels acting against God's will, or God failing to understand the consequences of Her decisions. But Aziraphale doesn't know that yet, and if he didn't go back to heaven he'd never figure it out.
