Trivia: In order to show that Eddie has severe hang-ups about his relationship with his mother, both his mother (in flashbacks) and his wife (briefly seen in the opening) are played by the same actress, Molly Atkinson, albeit in significantly different makeup and wardrobe to make it subtler.
Trivia: Bill Skarsgård has a lazy eye that he was able to train himself to focus in the same direction as his other eye. Thus, when Pennywise's eyes look in different directions, it's not an effect... Skarsgård is just letting his lazy eye naturally drift. His co-star Billy Hader didn't realise this and asked Skarsgård how the effect of his eyes focusing in different directions was achieved, assuming it was CGI. Skarsgård replied, "Oh, you mean this?" and let his drift sideways, horrifying Hader.
Answer: It's a bit involved, but the fact is that he was never that stable with the idea to begin with. He had forgotten all the horrors of his childhood (either due to the influence of Maturin the turtle [from the book] or Pennywise it makes little difference) and when it all started to come back to him, he panicked. And frankly, he had no way of knowing whether Pennywise could get him where he was or not. He didn't know enough to know one way or the other. But he knew that where Pennywise was concerned it would never be over simply. Pennywise would have tormented and tortured them like he did when they were kids, and when faced with that prospect he decided that ending it now, especially in his panicked state, was preferable to the idea of torture.
Garlonuss ★