...and an alien race has FTL space travel. We want access to their list of habitable planets, they want the secret to our gateway. Protagonist is a man created by the alien race, but does not know it. Falls in love with a woman that he shouldn't. Realizes he doesn't have memories of growing up. Can't say when I read it (more than 20 years).
This is The I Inside by Alan Dean Foster.
Published 1984. I read it when I was a young boy. The main character is a sort of bioengineered alien human hybrid, who has most of the abilities the aliens have but looks human. His name is Eric Abott.
He has a sudden glimpse of a woman in a car, and becomes obsessed with her. She falls in love with him too, but for various political reasons, they're not allowed to be together. They decide to escape to be together in a colony on the other side of the gate.
The aliens have a list of habitable planets from various automated probes, but they can't actually get to the planets without the gate. Eric is meant to be a deep sleeper agent who gets access to the gate, but the aliens fail to make him properly, and he ends up far more human than he should have been.