Although I’ve never referred to it as a Twin Flame relationship on Medium, I have written quite a bit about it. I hope this will help to answer your question.
We didn’t any of us understand until about 2 years in that this is what it was, but it was a huge relief to discover this term/paradigm because then a bunch of things suddenly made sense — the nearly instantaneous connection and feeling of not falling in love but meeting someone you were already always in love with. Then there was the overwhelming intensity, made more complex by the fact that we were each married to other people.
Although things are stable now, we still have a much greater element of ebb and flow, push and pull in the relationship than I do with my primary partner. It can be difficult and frustrating, even now that we know this is what the relationship is really for — that learning and growing piece. But he gets me like no-one else does even though we are so, so different in so many ways. I feel like we are the two sides of a coin — one is heads and one is tails, but we still go together.