Catholics too often forget that Our Lord Jesus Christ is in control of His Church. Catholics also all too often forget that the Pope is merely Christ's Vicar: the Pope, as every Catholic is, is bound to believe and obey everything Christ taught and everything that has been infallibly taught in the universal and ordinary Magisterium.
Certainly, a Pope can commit error in discipline and jurisdiction. We know, for example, that the suppression of the Jesuits by Clement XIV was a juridical act and it was wrong. But, it did not affect doctrine or practice. Nonetheless, due to the Pope being pressured by, in this case, Freemasonry, he did commit error and damaged the missionary activity of the Church. Disciple and jurisdiction play an important role in the Church: pray for the Pope!
A Pope can, however, err as a private doctor. Papal Sunday homilies, for example, are not protected by the guarantee of infallibility. Nor do Popes expect Catholics to regard such homilies as such. There is much confusion as to the extent of Christ's protection over the Pope: the Pope is not some automaton moved magically by Our Lord. He is a free human agent, open to sin. That is why we must pray and pray even more for the Pope! Lucifer and the hordes of hell target the Pope like no other person. If he can inhibit the Pope, cause disciplinary and juridical confusion etc. he can inflict immense damage on the Mystical Body. If he can goad on the "wolves" (who still dwell in the Vatican, and innumerable Chanceries) to manipulate and undermine the Pope, he will. But, let us not forget, even in such scenarios, Christ permits it: as a punishment for infidelity.
But to conclude; in answer to the immediate questions as to why the Pope will not try to change neither the doctrine nor the practice (for giving Holy Communion to Adulterers and/or acclaim that practicing homosexuality is approved), at the upcoming Synod on the Family, the answer is because Our Blessed Mother will be guiding him. These were the words of the Pope at Aparecida, on the 24th of July, 2013,as Pope Francis re-consecrated himself to Mary:
Mary Most Holy by the merits of Our Lord Jesus Christ, in your beloved image of Aparecida, spread infinite favours over all Brazil.
I, unworthy to be counted among your sons and daughters but full of desire to share in the blessings of your mercy, lie prostrate at your feet. To you I consecrate my intentions, that they may ever dwell on the love that you merit; to you I consecrate my tongue that it may ever praise you and spread your devotion; to you I consecrate my heart, that, after God, I may love you above all things.
Receive me, incomparable Queen, you whom Christ Crucified gave to us as Mother, and count me among your blessed sons and daughters; take me under your protection; come to my aid in all my needs, both spiritual and temporal, and above all at the hour of my death.
Bless me, heavenly helper, and through your powerful intercession, give me strength in my weakness, so that, by serving you faithfully in this life, I may praise you, love you and give you thanks in heaven, for all eternity. Let it be!