person who gets lonely easily; person who craves company
A slightly childish or affectionate term for someone who dislikes being alone and often seeks companionship. Similar to 寂しがり屋, but more colloquial and often used teasingly.
See also: 寂しがり屋
My child is a lonely-heart and always wants to be with someone.
He gets lonely easily, so living alone doesn't suit him.
Compound of 寂しい (sabishii, 'lonely') + ん坊 (-nbō, a suffix meaning 'person' or 'child', often used in affectionate or teasing nicknames). The ん is a colloquial contraction.