Is a father's obedience obligatory if he orders the boycott of a person with whom he has problems, and not to accept wedding invitations from this person, and what is the ruling on disobeying the father in that, knowing that a promise was made to attend and considering the distress this matter causes?

If the father wants to sever ties completely and abandon (the other party), then he must not be obeyed, because obedience to parents is obligatory in matters that do not involve disobedience to Allah, and abandoning a Muslim for more than three (days) is a major sin. If the father wants to cut off excessive connection without abandoning (the other party), then obey him. As for accepting an invitation to a wedding feast, it is obligatory according to Islamic law, so do not obey him if he prevents you from it. However, if he prevents you from accepting other invitations, then obeying him is obligatory.