Is it permissible to cut ties with a friend with whom you do not feel comfortable or with whom you feel bored when sitting, so that this would not be considered abandoning your Muslim brother?

The default is that it is permissible for a person to avoid someone and change their phone number, unless there is a dislike for them. However, Islamic law encourages eagerness for love and communication among Muslims, making it a path to Paradise. Among the causes of mutual love are spreading greetings (salaam), shaking hands, and exchanging gifts. Islamic law prohibits abandonment, quarreling, and severing ties among Muslims, as it is not permissible for a Muslim to abandon his brother for more than three nights, and the better of them is the one who initiates the greeting. If you do not refuse to greet him, you are not considered to have abandoned him. Loneliness can be removed through divine love and cooperation in good deeds, as "My love is due to those who love each other for My sake, sit together for My sake, and visit each other for My sake."