I did used to have this problem. T and I wrote a flashcard together about it. The flashcard says "Right now I am feeling like T doesn't care about me, but there is lots of evidence that he does" and then goes on with all the evidence. Also T suggested I record the sessions and listen to them later. Finally, we were able to text and email,and sometimes speak if necessary, between sessions. All these things were helpful and gradually I was able to "hold on" to the good feelings and learnt to trust. I've noticed that it has transferred across the rest of my life as well. I'm more able to trust friends and I don't any longer think that if one small thing goes wrong it means someone hates me or doesn't care. So it was really really good and helpful thing to learn.