It is strange, and a little mysterious. What I think is that another form of reality is settling in. By such love, the two have coupled as one unit, and in some heavenly sphere I believe Lawrence thinks they will be one, two halves of the male/female dualism. But that is in a heavenly sphere and they are still on earth and in the context of individual flesh and blood. Her insecurity is something that comes out of internal self (her ego I think L would say), a wall between her and him. I'm a little less certain on this that the other stuff I've explained.