Being in a place where you're holding on to a lot of bitterness, frustration, and resentment isn't good. Though some people are able to simply let things roll off their backs and get over them relatively easily, others have a more difficult time doing that, which can result in their harboring resentment, even if that wasn't their intention. How you deal with bitterness has a lot to do with your personality. And if you think your personality matches the traits ascribed to your zodiac sign, you may be interested in the zodiac signs most likely to harbor resentment.
Even if you do think that you perfectly fit with your zodiac sign, your individual charts (and corresponding personality traits, proclivities, and preferences) are more than just your sun sign, so just because your sun sign might indicate that you'd likely hold on to resentment and bitterness, it still doesn't necessarily mean that you do. Knowing how your zodiac sign (sun sign or beyond) can give you some insight into how you might interact with people — such as in the case of holding on to resentment — can help you not only understand yourself better, but also you better understand how other people might interact with you.