The boyfriend stated at the very start of the relationship that:
1. His teenage daughters came first.
2. That his job as a pilot came second. 
She accepted these terms. Now she is trying to alter them. Does she deserve to be put first every now and again? Absolutely. She needs to again decide if these terms meet her needs, or are something she is not willing to accept. The daughters will grow up and move on to their own lives and I'm sure more of the focus will be on her. But what happens when grandchildren enter the picture? Will she drop to #4 on the importance list? The fact is, she no longer likes the terms of her relationship. SHE SHOULD MOVE ON!