Hello dear friend!
Well, the Orthodox Church does not allow intercommunion in recognition of the fact that there is currently no Eucharistic (or dogmatic) unity between the Roman Catholic and the Orthodox Church. Moreover, Orthodox bishops do not allow the members of their flock to receive Communion at Roman Catholic services, except for truly unique circumstances.
For Orthodox Christians, the Eucharist is a visible sign of unity; to receive the Eucharist in a community to which one does not belong is improper. If one does not accept all that the Church believes and teaches and worships, one cannot make a visible sign of unity with it. The Eucharist is the result of unity, not the means by which unity is achieved.
I hope it answers your question,
God bless you, greetings from Greece!