To be less tongue in cheek: it's not that we're trying. I know outwardly we seem very similar and we share far more basic doctrines than we share with Protestants. But our communions have been separated for just shy of 1000 years. Those "basic doctrines" have been subject to Newman's beast in that time.
Laying aside the filioque question, we have diverged on doctrines such as the Essence/Energies distinction, purgatory, papal infallibility, mortal and venial sin, original sin, transubstantiation, the Immaculate Conception, the "indelibility" of priesthood, and we have never declared that any rite is verboten for translation into vernacular. That's all off the top of my head and without racking my brain.
I know a lot of Roman Catholics are hurt because your church teaches that (since the lifting of the anathemas and Vatican II) we are welcome at your table, yet ours does not reciprocate. But very real differences have developed between Rome and the East. We have no wish to try breathing with "two lungs" when one of those lungs is still, to all appearances, a collapsed lung.