An expression that indicates a strong or overwhelming feeling or sensation (e.g., 'I feel terribly.../I can't help but feel...'); attaches to the て-form of verbs or adjectives.
来週の発表が心配でならない。
I'm terribly worried about next week's presentation.
久しぶりに会う友人のことが気になってならない。
I can't help being curious about the friend I'll meet after a long time.
赤ちゃんの成長が嬉しくてならない。
I'm extremely happy about the baby's growth.