Why I feel this way?

Now me and my ex broke up like 10 months ago from today. And we had 8 months of good relationship. But I just find myself suddenly having nostalgia about her. Since today is the last day of 2024 and its gonna be new year. Makes me just realize that, she's not here anymore. While on 2023, I enjoyed a lot of moments with her during the 2023 to 2024 new year. While she was verbally abusive and never knew how to kept promises and she had some male attention issues. She bought me a cake on my bday and everything was okay. She called me controlling since I suggested her to take her brother with her if she is going somewhere since I dont want her to have creeps following her around. If she didn't broke up w me. Probably we would be planning for marriage soon or an engagement. Sometimes I just feel like she's my soulmate.
We broke up due to mutual issues. She had her own bad doings. And I had mine.
Although I rejected her offer to friendship since at that time I was on a worse state of health.
I just dont feel the hopes of finding someone who can just... make me feel the same again.
I saw a new dp of her on socials, since scrolling.
And she was looking beautiful.. although I remind myself about her harsh words..
My heart is stubborn.
Any suggestions or help?
Why I feel this way?
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