regretful

adj.

后悔的；失望的；令人惋惜的；遗憾的

1. I am regretful for what I have done.
   我对我的所为深感遗憾。
2. I am regretful for hurting her feelings.
   我后悔伤害了她的感情。
3. I am never regretful to choose the major by now.
   我至今仍不后悔我选择这个专业。

Rent seeking with regretful agents: Theory and experiment
The role of regretful thinking, perseverance, and self-efficacy in venture formation
Reversal Surgery in Regretful Male-to-Female Transsexuals After Sex Reassignment Surgery
Evaluation of road construction alternatives: A regretful approach
S315: Reversal surgery in regretful male to female transsexuals after sex reassignment surgery
Regretful Liaisons: Exploring the Role of Partner Regret in the Association Between Sexual and Relationship Satisfaction
Regrets, I've Had a Few: When Regretful Experiences Do (and Don't) Compel Users to Leave Facebook
Are Perseverance and Self-Efficacy Costless? Assessing Entrepreneurs' Regretful Thinking
Inventors and New Venture Formation: the Effects of General Self‐Efficacy and Regretful Thinking
Why do online tourists need sellers' ratings? Exploration of the factors affecting regretful tourist e-satisfaction