From The Power of Now:
"The reason why the romantic love relationship is such an intense and universally sought-after experience is that it seems to offer liberation from a deep-seated state of fear, need, lack and incompleteness that is part of the human condition in its unredeemed and unenlightened state.
[When you live purely in the mind, you feel fear and neediness and no sense of lasting fulfilment]
But then that special relationship comes along. It seems to be the answer to all the ego's problems and to meet all its needs. At least this is how it appears at first. All the other things that you derived your sense of self from before, now become relatively insignificant. You now have a single focal point that replaces them all, gives meaning to your life, and through which you define your identity: the person you are "in love" with. You are no longer a disconnected fragment in an uncaring universe, or so it seems. Your world now has a centre: the loved one. The fact that the centre is outside you and that, therefore, you still have an externally derived sense of self does not seem to matter at first. What matters is the underlying feelings of incompleteness, of fear, lack and unfulfillment so characteristic of the egoic state are no longer there - or are they? Have they dissolved, or do they continue to exist beneath the happy surface reality?
If in your relationship you experience both "love" and the opposite of love -- attack, emotional violence, and so on - then it is likely that you are confusing ego attachment and addictive clinging with love. You cannot love your partner in one moment and attack him and her the next. True love has no opposite. If your "love" has an opposite, then it is not love but a strong ego-need for a more complete and deeper sense of self, a need that the other person temporarily meets. It is the ego's substitute for salvation, and for a short time it almost does feel like salvation."
[This type of pattern can only be avoided if you both agree that the relationship will be part of your spiritual practice -- that you will both listen and give space to the other person and do not create a relationship around the mind and the demands of the ego.]