After feeding the three uninvited guests, why did Dev feel disappointed and write a letter to Jog?

Dev felt disappointed because he was expecting Sai Baba to personally attend his Udyapan ceremony, as promised. Even though three uninvited guests—the Sanyasi and his two companions—arrived and were served a meal, Dev remained uncertain if this was Baba's way of fulfilling the promise. Chapter 40 explains that "the doubt remained in the mind" and this veil of Maya prevented him from recognizing the event's significance. Feeling that he had not received the direct experience he had hoped for, he wrote a letter to Jog expressing his confusion. In the letter, he lamented how Baba had seemingly deceived him and questioned why he was left feeling disappointed despite having invited Baba with such love.