It all starts with this post where the mod of /r/waifuism admits that she has started to acquire feelings for another character, but still loves her previous waifu. The comments then discuss what waifuism "should be" with some people for it, others against it.

One user creates a thread complaining about poly-waifuism and how a relationship between one and their waifu is special and should be considered monogamous.

One user goes as far as to create a poll on whether waifuism should allow polyamory or not.

Eventually ending with the mod stepping down.

My favorite comment from the thread. https://np.reddit.com/r/waifuism/comments/43up4h/a_farewell_to_the_reddit_waifu_community/czl4aih