You came looking for the aspect that explains why what you say and what you want keep pulling apart. It is a real pattern. This is not where it lives.
What it looks like in a life
Mercury and Venus stay close because both orbit inside Earth's path around the Sun. In a real chart they sit in the same sign, or one or two signs apart, sometimes conjunct, occasionally sextile. The friction people call a square usually comes from Mercury square Saturn, Venus square Mars, or a Mercury and Venus in neighbouring signs that want opposite things. Gemini Mercury with a Taurus Venus feels like a fight. It is not a square.
The gift
Ruling this out stops you from building an explanation on something that cannot exist.
The friction
Some report generators print this aspect with a stretched orb. If yours did, check the degrees, then read the rest of that report slowly.
The esoteric layer
Traditional astrology measured Mercury and Venus by their distance from the Sun and by whether they rose before it or set after it, never by angles their orbits make impossible.
Where this goes
The aspects these two actually make hold the pattern you are after. A full natal reading reads them in order.
Related
See it in your own chart
Cast your chart free and read this placement next to everything else you carry.