Retrograde is when the planet's direction of travel though the zodiacal constellations appears to temporarily reverse from our vantage on Earth, not that planet's position in the sky.

The following is an oversimplification, but Mercury and Venus spend a lot of time in retrograde because they are inside our orbit; they are in retrograde for much of the half of their orbit they pass between us and the sun. For planets outside Earth's orbit, they are in retrograde less often, basically when Earth is passing their (slower) orbit up.

Planets orbit faster the closer they are to the sun, so retrograde events happen frequently for Venus and Mercury, providing plenty of excuses for miscommunications and frustrated love.