The art of losing isn’t hard to master (1.1, 2.6, 4.12)
This confident, if rather odd, statement immediately covers up any emotion that "losing" might create in the poet.
I miss them, but it wasn’t a disaster. (5.15)
Though the poet admits here that she misses the places she loved and lost, she is still reluctant to say that any loss is disastrous; instead, she is resigned to the continual loss of things she loves.
It’s evident The art of losing’s not too hard to master Though it may look like (Write it!) like disaster. (6.17-19)
This breakdown in the familiar structure of both refrains finally betrays the poet’s real feelings – the loss of the loved one addressed here forces her to admit that some losses really do look and feel like disaster. The parenthetical command to "Write it!" shows us her own reluctance to admit to these feelings here.