The plain verse in (Genesis 12:12) is a husband's anxious calculation: when the Egyptians see thee, they will say, This is his wife, and they will kill me, and thee they will keep alive. Targum Pseudo-Jonathan follows the Hebrew Bible here with almost no embellishment — and the restraint is itself the point.
This is one of the few moments in the Abram cycle where the Targum refuses to rescue the patriarch. It could have smoothed the verse. It could have inserted a divine oracle telling Abram to lie. It does not. The Aramaic lets the fear stand naked. Abram is frightened, and he asks Sarah to say she is his sister, and he knows exactly what he is doing.
The honesty is devastating. The man who will father a nation is also the man who, in his first real crisis, asks his wife to protect him with a half-truth. (She was his kinswoman — see (Genesis 11:29) — but she was also his wife.) The patriarchs of Jewish tradition are not carved from moral marble. They are carved from fear and faith braided together, and at the border of Egypt the fear is winning.
The Targumist's restraint teaches a lesson. The tradition could have airbrushed Abram. It did not. The Torah, and the Aramaic that reads alongside it, have always preferred the flawed covenant-bearer to the flawless fiction. Abram's fear at the border of Egypt is preserved because we, who face our own borders, need to know he was afraid too — and that the covenant survived his fear.
The next verse will be worse. Sarah is taken. The lesson continues.