My ex dated another girl just a day after our breakup?

Was he sincerely in love with me? He literally vowed that I'd be his first and last love but guess that isn't what's written in our fate lol. He was the sweetest guy ever tbh he even wrote 2 books about me and wrote a love para everyday, rejected every girl for me, never batted an eye over any girl, consoled me, was everything you could ask for in a boyfriend but like.. he seemed totally in love that I couldn't accept the fact that he found someone else and moved on in such a short duration..
My ex dated another girl just a day after our breakup?
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