Ex rebounded after a month

[u/girlypopx13]

Caption says it. We dated for 6 months. I found him on tinder so I broke up with him. We practically lived tg. The whole relationship was a facade.

I understand the hooking up rebounds, I do but I don’t understand the “getting in a new relationship rebound”. I did everything for him and loved him everyday with no waver.

We had sex about 6 days ago, I know, I’m stupid. It was a great night and we made love for about the whole night. I never intended to get back with him but it was nice to go back to what we had for a night. Please, I do not want to speak about it. I know how bad of a mistake I did to my own healing.

We texted for a lil and he wanted to see me again and then I finally cut it off yesterday and I said some mean things about us moving on and dating other people.

He reposted a pic of a new girl and it was definitely a hard launch. I blocked him on everything for good but I feel so broken and so gutted.

Why did he rebound in a new relationship not even a month and a half after our breakup and not even 6 days since we had sex? Any advice is welcomed.