1) Atoner 2) Bemoaner 3) Certain second-guesser 4) Confession participant 5) Confession participant, often 6) Contrite fellow 7) Contrite one 8) Contrite person 9) Contrite type 10) Disappointed one 11) Hand wringer 12) He feels remorse 13) He regrets 14) Monday morning quarterback 15) One feeling contrite