There will come a point in your life where you are afraid to say something because of the tension that it may cause, the relationship that it may strain, or the chaos that it may create. When you feel that way, speak up anyway. Do not let your voice be small just because of the consequences.
There is a reason that you have the opinions that you do, and you are allowed to have them. If you feel a certain way, you should say it. There is a possibility that it may create some sort of mayhem, but there is also a chance that it could create something beautiful. That is worth being brave for. When the time comes for you to speak up and have a voice, let your voice be heard. The amount of change that you could enact by simply letting your voice be heard is unknown.
You could move mountains and start a revolution and all you have to do is open your mouth.
If you are afraid of what your words will do to the relationship, remember that relationships are built on more than words, and it takes much more than words to tear them down. If someone disagrees with what you say, they will contest it. You could easily discuss your points and reach a conclusion respectfully. Your relationship is going to be alright, but you need to have complete honesty. You need to be comfortable with speaking your mind and telling the truth, your truth.
Nothing that you say will create any more tension than the things you don't say. Think about all of the things you have held back in the past that you could have just said and how wrong they have gone. Wouldn't it have been better to just open up? Be open with who you are and what you want. Tell people what they mean to you. Life is short, and some things only happen once.
Speak your mind and don't hold back. You could miss the chance of a lifetime. Use the voice you were given and change the world. Someone has to do it.