I hope you can offer more than that and security. A dildo, healthy bank account, and a baseball bat would otherwise replace you.
You read like someone addicted to being in love and when that tamps down, as it always does, you want to get that high back. Perhaps you are capable of deeper connection, maybe not. If it bothers you, explore why. And wanting your own company does not necessarily make you emotionally unavailable - it makes you an introvert. But if you are really unable to connect deeply then being a secondary may work for you. But every one I know in a triad says they are a shit ton of emotional work. That may not work for you.