It is really hard as when he's not being a Narc he's very loving and we are very happy. It's like he can switch it on or off. He's in loving mode at the moment, but that's probably because I'm being off with him.
You are looking at two sides of the same coin.
It takes a lot of energy to be actively abusive.
However, very importantly, part and parcel of the way abuse works is to cause you to feel you are in control of how it goes.
Nobody would stick around to see what happens next unless there was some element of mystery to it. Nobody would stay with a partner who was 100% horrible all the time.
Abuse couldn't work on a long term basis if the victim (you) didn't feel some sense of obligation to try to work on the relationship or some sense of optimism that you could find the right formula (or it could be found by a therapist), and all would be well. Magical thinking begins to surface when faced with the incredibly confusing signals you are getting.
How does the abuser guarantee that you will stay? You get an episode that does your head in, but soon all is normal again (as normal as he can make it appear anyway) and you think you should give it a chance, you think 'for better or for worse', or you get the feeling that you are the special one who will find the key to his heart.
So you stay and you try to make progress.
Next time you catch yourself thinking that you need to explore all avenues, try clapping with one hand. How did that work for you?
I wish you luck at therapy.