No, you are not out of line to feel disrespected in this situation. In a healthy and committed relationship, communication, trust, and consideration for each other's feelings are essential. Your partner staying out all night without any communication or explanation can understandably be upsetting and hurtful.
While it's normal for people to have their individual activities and occasional nights out with friends, it's equally important to maintain open communication and inform each other about plans or unexpected changes. Failing to do so can lead to feelings of neglect, worry, and disrespect.
It's crucial to address this issue with your partner and have an open and honest conversation about how their actions made you feel. Effective communication is key to resolving conflicts and maintaining a strong and healthy relationship.
During the conversation, express your feelings calmly and assertively, and try to understand their perspective as well. It's possible that there might be a reasonable explanation for their behavior, but regardless, they should be willing to listen to your concerns and work together to find a solution that respects both of your needs and boundaries.
Remember, in a long-term relationship, both partners need to feel valued, respected, and supported, and it's essential to address any issues that may arise to maintain a strong and loving bond.