In relationships this Mercury values being able to predict the weather. I tend to see the same picture again and again: the partner isn't chosen for the sparks on the first evening, but for how good it feels to sit in comfortable silence by the third meeting. Conversations about feelings don't happen every day, but when they do they carry weight. If someone with this placement says "I love you", you can take it that they've been thinking about it for a long time before the words came out.
The everyday running of a relationship gets discussed in concrete terms: the budget, the holiday, the work on the flat, the plans for the year. Mercury in Taurus can't bear it when ordinary practical decisions get wrapped in a thick layer of emotion. "Just tell me what it costs and when we're doing it" is the kind of line that comes naturally here. The same is expected back: clarity, constancy, promises that actually get kept. Words thrown off in passing, plans forgotten by the next day, a loose attitude to what was agreed — all of it quietly accumulates, and one day it spills out as a cool, scandal-free parting rather than a row.
In conflict this mind goes quiet first. The partner often assumes everything is fine, when in fact a slow processing is underway inside. A day, a week, sometimes a month later the person comes back to the subject and says what they've worked out, which can take the other side by surprise because they'd long since forgotten the disagreement. So a plain piece of advice, if you're with a Mercury like this: don't push for the conversation right now, and don't read the silence as agreement. Give it a pause, then ask the next day what they actually make of it. None of this is fixed in stone — it's a pattern worth noticing in yourself, not a script you're bound to follow.