Yes, it can be a dilemma, apparently uniting when there are so many serious differences. However, I doubt that, at the moment, there can be a merger of Roman Catholicism and Orthodoxy. I am a member of the Syriac Orthodox Church and for the past 25 years we have enjoyed a very close relationship with Rome, enabling us to commune each other and offer each other pastoral care. Yet this has not meant that differences have been put aside. We Orthodox still believe in the equality of Bishops, not the primacy of the Pope; we have not incorporated the filioque in the Creed etc etc. What is happening is that two Churches are trying to act as closely together as possible, believing that common prayer and worship will lead to us becoming worthy of the Holy Spirit's giudance in how to overcome our differences.
Yes, Christ is One, the Church is One, and we sinful human beings can only pray and act according to Christ's commandments in pursuit in a public union that is truly of His Divine Will.