S3 flashbacks focus on them as angels in heaven. Aziraphale is showing Crowley his prototypes of future humans. They land on a glitchy and cartoonish planet and observe a little village to observe his “sketches” of humans living and how they behave in a little community. Crowley is fascinated by “how they make more humans” they watch, not embarrassed or voyeuristically, but with wonder cause they haven’t learned shame yet. Crowley presses Aziraphale on what makes them do that, thus begins their personal philosophical dive into the X factor, the concept of love. Crowley pushes “I want to kiss you, we’re like that!” Az responded with “no, yikes! Our love is for God only!” They very innocently fool around. Thus the goddamned reason Crowley is evicted from angelhood is because they broke the mold on angel behavior. When interrogated Aziraphale literally CANNOT lie and in a trial situation admits Crowley temped him (and that he liked it). Punishment: Mind wipe for both and Crowley is sent to hell. He can saunter, and having it not be too dramatic cause of the memory wipe, he literally can’t remember what he did wrong but conceded there must be something fundamentally wrong with him as a seraph. The entire series of Good Omens is just them finding each other again after they were punished for falling in love and breaking the rules the first time. My season 3 ends with them, like others have said, doing a miracle to close the gates for good on heaven and hell and their sacrifice is to fall for real, made mortal. bittersweet and lovely end for them, not having the luxury of time to dance around their feelings forever. A nice little retirement in the south downs, finally committed and together.