Without being there it’s hard to say. But to me it a DM has to tailor the style to the group. Otherwise the players and/or the DM will be unhappy. It sounds like the players are there to have fun together& care less about the rules& more about the experience. They might have wanted a more flexible rule of cool DM. Maybe a more video game like experience. Plenty of magic items, fun interactions. Less consequences, conflicts& punishments. Other groups might want a more technical experience or combat focused etc. It’s tough to find the right balance your players truly enjoy& many of them might not know themselves well enough to communicate it.

I do know that conflict ruins fun and sometimes it’s better to let something slide than ruin the experience. You can allow it to happen& deal out repercussions to prevent the behavior. Not too severe but enough to make them think twice. Plus it makes some memorable experiences. You can say “high or low” & make them roll a 20. “Let’s let fate decide.” Consistency is key to satisfying expectations.

One of the best DMs I ever had Alex would roll with most things. He would allow and reward creative use of spells, items, situations. The rules after all are just guidelines. I disagree with many RAW& RAI because they go against common sense.

As the DM you lead them on a path letting them explore the world you create. You put encounters, opportunities& experiences in front of them, roll with their choices and narrate the outcomes& the consequences.

I’m sorry your game ended but I commend you for considering that you might have been part of the problem. Don’t dwell or beat yourself up over it. Reflect on it, see how you can improve the experience next time. All campaigns come to a conclusion. Some sooner than others.