Though there are physical similarities of a sausage and your brain (some form of protein neatly packed in membrane), the real semblance is in their function. Your brain, like a sausage tube, has a certain capacity for rational and logical thinking. When your brain is filled with rational thinking, that’s the time to create life-guiding principals and decisions such as how much of a house can you afford or what kind of car you need BEFORE you see the flashy Mini-Cooper S.
This is especially true in the realm of relationships. How late will you date? Should you be alone with your significant other when not in a public setting? Will kissing be allowed on your first outing? Before the emotions of enamor, infatuation, longing, liking, lusting and love begin to squeeze out the rational material from your brain, boundaries must be set. The longer your relationship grows, the more rational material is methodically squeezed out of the other end of your brain until one day your emotion filled meat head is able to rationalize any thought or action without regard to the consequences.