Fixing hurt feelings with your boyfriend doesn't necessarily mean extending numerous apologies, taking full blame and resolving to "never do it again" only to find yourself with the same issue a month later. Often relationship issues involve hurt feelings on both sides that need addressing. When you and your boyfriend are ready to talk calmly about one another's concerns, set some guidelines for positive, open communication to deal with the problem.
Validate your boyfriend's feelings by acknowledging and accepting them. Say something like, "I know it hurt you when I didn't end up going to the concert with you. I'm sorry you're sad." This lets him know that you're aware of the specific issue and that you want him to be happy.
Express your side of the issue by using "I's" instead of "yous." Say things like, "It made me feel guilty when you ..." or "My thoughts were ....." Using "you" often seems accusatory and puts responsibility on your boyfriend, rather than seeing it as a mutual issue both of you must come together to solve.
Listen to what your boyfriend has to say. Focus on what he's saying before thinking about what you'll say next. This is important on both sides so each person feels truly heard.
Remind your boyfriend of the specific things you love about him. Sometimes one or both people in a relationship may feel insecure about why the other is with him. Giving him specifics may help alleviate hurt feelings and reassure him that you respect and appreciate him for who he is.
Resolve to express your own needs and concerns in the future, and encourage your boyfriend to do the same. Open communication is important in a healthy relationship, and hurt feelings may simply be a lack of understanding how the other person truly feels. Speak your feelings and thoughts respectfully but honestly, and let your boyfriend know it's safe for him to do the same.
Plan how you'll deal with similar situations in the future, as a couple. Clearly and respectfully state your expectations for your boyfriend. Repeat what you understand are his expectations of you, and name ways you can help steer your own behavior in a more positive direction.
Agree to disagree on something if you can't see eye to eye. Let your boyfriend know that you accept the difference of opinion, but that you both need to do so and move forward. Confide that you know he'll do the same. However, do not ignore issues that present themselves several times, because they usually indicate a larger related problem.