Feeling sorry and wishing that something had not happened. (Cambridge Dictionary)
If someone is rueful, they feel or express regret or sorrow in a quiet and gentle way. (Collins Dictionary)
Exciting pity or sympathy: Pitiable. (Merriam – Webster)
Expressing sorrow or regret, especially in a wry or humorous way. (Oxford Dictionaries)
Sad rueful depressed cheerless man.
Rueful other words. Thesaurus. Plus.