Roleplay Helped Me Appreciate Mom

A better ending would have been for the neighbor to share him with his mom.

If his mom had found more evidence to make her question what was going on, she might have confronted the horny neighbor. That neighbor (whom you never named) could have admitted what she'd done, and then offered advice on how the mother could come to terms with her own libido. The neighbor might even have had sex with the mom. Hell, they might have had a nice little threesome!

The way it ended was almost as abrupt as how the story started.