A strange star-like object
If it disappeared towards east or so, as I  think because the other "star" should be Venus, that it can be a satellite - or even more an airplane - as seen from "its rear". Basically at first it went far along the line of your line of sight looking still, until finally you could see the curvature of its path. From crude geometric feeling it was most likely an airplane, a lower altitude make it easy the seeing "from the rear" (think about what you see observing the rear light of a car moving on an horizontal road towards a down hill. It looks more or less two lights in the dark then it disappears. Or a ship approaching horizon). About absence of blinking: if it indeed was an airplane mirroring the sunlight, not way to see the less intense "navigation" lights.