Relationships change over time, which is why Donald Trump would have advised Paul McCartney to sign a prenuptial agreement before he married. While no one likes to prepare for the breakdown of a relationship, when it comes to the academic scientist and private industry, it is in the best interests of both to adequately prepare for a bumpy future.
If you find yourself being pursued by industry, remember what a company ultimately wants: product. In the beginning of a relationship, a company is interested in finding out all it can about a research area and working with a particular academic group because of its expertise. However, over time, circumstances change and interests deviate. The company needs a commercial product, and at some point they will insist on graduating from supporting academic exploration to product development. You, however, may feel you are not ready, that there is more research to be...