I have to admit
i love this girl and I feel that
she is going to be the one i marry and spend the rest of my life with, But lately
I've been questioning myself if its worth working this out. The reason I say this is...
It doesn't matter why. The answer to your title question "is it me or is it her"... it's you. You're absolutely all over the place, even in a single paragraph talking about her you are running in both directions.
The problem is you.
Stop thinking about marriage. Stop considering "til death do us part" and "forever". None of that is on the table right now.
Right now, the only thing on the table is where you are going to dinner next, or your next movie. You don't predict the future, you live in the now. It already didn't work out once, you already suspect it won't work again... (see your quote above)
Since no one here can know better than you what's going on, my best recommendation is just calmly take this ride. Don't predict, don't force, don't need anything other than relaxed dating. It is MORE likely to not work out than it is to work well, so don't make it into something it isn't... yet.