Ancient age, or medieval age pre-astronomy. Suppose you are the Romans (what else? ) On a nearby island, connected by sea tiles, there's France. France has the Great Lighthouse, so it can trade via sea tiles. France creates a colony on your island, and build a harbor in it. You build a road connecting the French settlement to your existing road network, thus establishing a trade route between Rome and Paris. You decide to trade some goods. Then, while the trade treaty is still active, the french colony flips to Rome. Since Rome cannot trade via sea squares at the moment, the trade treaty ends abruptly. The question is: do you suffer a reputation hit or not?