Dear one, I am here to tell you that it is NOT your job to make other people happy - just like it is not their job to make you happy! You, just like everyone else, have the ability to make and keep yourselves happy.
You also do not have to agree with everyone you talk to. It is okay to have disagreements with someone and it is okay to not think the exact same way as another person. It is not okay to get reactive. if someone is passionately saying the sky is purple when you know it is blue, it is perfectly fine to say "okay, if thats how you feel" and walk away. Maybe even change the subject. This is setting a boundary with yourself; when someone disagrees with me, I will not feel the need to prove myself or force myself to agree with them - I will honor how I feel - and let myself think for myself.
Learning how to set boundaries is also about learning about why you do not know how to set boundaries. Learning how to love yourself is the first step in setting boundaries.