The Catechism of the Catholic Church, on the topic of Jesus being crucified, states:
Catechism of the Catholic Church 612
612 The cup of the New Covenant, which Jesus anticipated when he offered himself at the Last Supper, is afterwards accepted by him from his Father's hands in his agony in the garden at Gethsemani, making himself "obedient unto death". Jesus prays: "My Father, if it be possible, let this cup pass from me..." Thus he expresses the horror that death represented for his human nature. Like ours, his human nature is destined for eternal life; but unlike ours, it is perfectly exempt from sin, the cause of death. Above all, his human nature has been assumed by the divine person of the "Author of life", the "Living One". By accepting in his human will that the Father's will be done, he accepts his death as redemptive, for "he himself bore our sins in his body on the tree."
Notice above that the Catechism appeals to Matthew 26:39 in order to teach that, "By accepting in his human will that the Father's will be done, he accepts his death as redemptive", being careful to specify that this was done in His "human will", as opposed to His "divine will, which he has in common with the Father and the Holy Spirit" (Catechism of the Catholic Church 482).
The verse in question says:
Matthew 26:39 (ESV)
39 And going a little farther he fell on his face and prayed, saying, "My Father, if it be possible, let this cup pass from me; nevertheless, not as I will, but as you will."
Notice that the above verse, under the Roman Catholic Trinitarian interpretation, would have Jesus saying, "Nevertheless, not as (I will in my human nature), but as (I will in my divine nature)", because His divine will is shared with the Father and Spirit. If the Being Jesus Christ can say "not as I will", but in reality is submitting to something that He does in fact will, in another nature, then how can it be said that there is meaningful submission taking place? If there is only a single Being involved in this situation, how can Jesus say "not as I will", without any qualification or explanation?
Additionally, the Catholic Church specifically teaches that Jesus possessed a "human intellect and will, perfectly attuned and subject to his divine intellect and divine will, which he has in common with the Father and the Holy Spirit" (Catechism of the Catholic Church 482). So, His "human will" was always "subject" to His "divine will". Therefore, in this system, He has a "human will" which is dominated by a "divine will", and the passage in question is an instance of the human will submitting to the divine will, as it always does.
The above reading of the passage in question is extremely complex. It has Jesus appearing to say what to any observer would indicate that He, Jesus Christ, did not want something, but was submitting His will to another, namely, God. However, the Roman Catholic Trinitarian interpretation of this verse posits the presence of an edifice of implied Trinitarian theology within that statement, in order to say that in spite of making a statement like this, Jesus was still fully God, and shared in the divine will.
Consider which interpretation makes more sense, and takes the statement as it appears, and which is reading a pre-determined theology into the passage. Notice that neither Jesus nor the New Testament authors felt a need to qualify what Jesus said here. That is good indication that the passage says what it appears to say - that Jesus is submitting His will to the will of God, demonstrating that they are distinct.