Regret is a feeling of sadness or disappointment about something that happened in the past, or not doing something that you wish you had done. Full definition
And I do not regret not trying on an eight. (gnomelover.com)
It's classic, forever, and I kind of regret not buying it (I bought a slightly more trendy version instead, with big sleeves, as seen above). (featherfactor.com)
Many divorced individuals express later regret about not trying harder or exploring more deeply what was possible for their marriage. (moderncommitment.com)