TPLF was rather dependent on the EPLF. It wasn't really a choice. There were several opportunities for an agreement on decentralisation or federalism that would have allowed Eritrea to remain part of Ethiopia- all of which the TPLF rejected out of hand. Having the EPLF as a force in a united Ethiopia would not allowed the TPLF to enjoy the free reign over the country it did after separation.
Even during the war, Meles resisted calls to press towards Assab, Asmara, and generally take over the country.
Thanks. Never thought of it in that way but what you said makes a lot of sense. Another question I have would be what is the TPLF opinion/position of Haile Selassie. Obviously a common enemy of Derg would make TPLF have a positive opinion of Haile Selassie, but if I remember correctly the entire TPLF uprising was justified as an echo of an earlier Tigray uprising in the 1940s of which the opponent was the Haile Selassie regime.