You don't fire your girlfriend in tough times, but your boss will fire you if he had to. It's a stricylty pay to play relationship.
Spouses are loyal back, businesses are not.
Not saying that you should be concerned about getting fired everyday. But if you don't create demonstrable value to your company over a longer period of time (a couple of years perhaps) don't expect to keep the job. Things are moving wayy too fast today.
Outside of my own direct experience, I can also recall many other co-workers' experiences where the companies I've worked for went above and beyond in their commitment to their employees. One time that meant making many extraordinary allowances for an employee suffering from a mental breakdown. At times it has meant extending the employment of someone who was looking for a life/career change, but the company kept on paying a salary until the employee found somewhere new to land - way beyond where the employment had any real benefit to the company. There are many others.
By all means, takes some precautions. By all means, stand up for yourself. By all means, make sure that you're being fairly compensated... but if you go into every relationship, personal or business, with your shields raised and phasers set to kill - you will reap what you sow.
I know that personal relationships aren't exactly the same as business relationships, but to pretend that they aren't somewhat analogous doesn't line up with my own experiences. I've had a lot of personal relationships in business. Almost every boss I've ever had has been my friend on some level and the same goes with a lot of people who've worked for me.
When you treat people with respect, consideration, and friendship in your work life - you'll be surprised at how often you get the same from them in return.
Getting independent information of your value isn't "guns blazing."
Going out and getting a job offer is a step beyond that.