The emotional intensity you'll display as this relationship begins may be very seductive for your partner. They'll remember you, after all, at a subconscious level, from a long-ago lifetime when you were lovers. But betrayal broke your trust for each other then, and the experience of that emotional pain is still present in your souls today.
Thus, when you get together in this lifetime, there will be a strong sense on both your parts that you were meant to come together and work things out once and for all. But your emotional intensity could sink the boat once again if you're not careful how you treat your partner. Your jealousy and possessiveness could easily get out of hand in this relationship, because you're still smarting from that past-life betrayal. Even if you were the one who did the betraying, you were still left with a feeling of suspicion, because you don't want the same thing ever to happen to you. Your methods of self-protection with this person will involve emotional control, romantic obsession, manipulation and more, all in a bid to wield complete control over your lover so that they never do anything you don't expect -- in short, anything that could hurt you. But in trying to control them, you'll be hurting them. The only way to resolve this karma between you will be to let go of your need to control the situation and let down your guard so that your vulnerability can shine through. Only when you learn to talk about your feelings instead of acting on them will you be able to develop a sense of trust and love.