You don't necessarily need to stay detached, it's more so "managing expectations".

But if this is true:

> Not when sex is involved. I literally cannot seperate my emotions from it

You've learned something valuable! Again, you'll likely eventually be thankful for this relationship, heartbreak sucks, but we eventually grow from it, don't get bitter from it. You are a living, feeling human being and that's okay!

So, next relationship, take your time to really date someone, to get to know them, so you know you two are on the same page. To start, you need to hear that they are at least open to a serious relationship. Or else, why even have a first date?