There is this mistake that some people make when they work in a company with others make, which is the assumption that their colleagues at work are their friends. With that assumption you find many people becoming too friendly with colleagues that they start sharing personal information and opinions about work to them.
Making friends with your colleague at work is not a bad thing, just make sure you are making friend with a right person, don’t try to make friends with everyone you see, you can just make friends with people you think they are reasonable and are worth being friends with. There is something some people don’t understand, even if you have a friend, you are not suppose to share all your personal problems with them, something’s are suppose to be kept to yourself, someone you call a friend today, might end up being your enemy tomorrow. You only know about your intentions towards people, but you don’t know people’s intention towards you.