When did you know you were ready for a divorce?

I want to know when you knew you were ready for a divorce. I am currently feeling vulnerable, and have reached a stage in my marriage of 4 years where I believe I have completely fallen out of love with my husband. Thankfully I have no kids so I feel like it would be easier for me to leave, but somehow I’m scared to take that step. It’s sad because even a small helpful gesture from a stranger makes me fall in love with them I think it’s how vulnerable I am at the moment but my husband has failed in every aspect, I know we don’t love each other anymore and it makes me jealous seeing happy couples knowing that could never be us.