If you've felt comfortable together right from the beginning, you probably think it's a good thing -- after all, who wouldn't want that wonderful sense of familiarity with someone they've met, who makes them feel like they've known each other for years? Except in this relationship, it could actually be less of a sign that you're so similar and in tune, and more that you're subconsciously attracted to each other because you're acting out an old relationship. It could be one from your past in this lifetime or it could even be that the two of you were involved in a past life, but either way, the result is felt in the now.
If you're acting out an old relationship, even if it was a good one that gave you a lot of confidence, love and support, you're still shortchanging yourself with this person. Even if you felt like you knew each other instantly, you don't. And even if you want to recreate something that was just so wonderful a long time ago, you should still give this person and this bond a chance. You might discover that you actually create a connection that's even better than the old one. Do each other the service of getting to know each other as the individuals you truly are, not the people you're projecting onto each other the way you'd project a movie onto a blank screen.