Ex-gf and I tried to get back together, but it felt like something was still broken?

We broke up with each other several times already, and each time we got back together without a hitch... until the next break up. This time, however, when we tried to get back together, it didn't feel authentic. It felt like we were both putting on a facade, like we were forcing something that was no longer there. So we agreed to break up for good this time. This time, it felt like something was really broken that could no longer be mended. Your thoughts?