Opinions differ - both on people and things. Maybe you've written a poem you consider to be a 10/10. Someone else comes along and gives it a 4. Sucks, doesn't it? But there's little we can do about it except try to understand why they gave it a 4. Maybe you could also explain why you think it's worth a 10. However, we can't always talk about it like that. Sometimes the other party's just not willing or we are unable due to circumstances. Don't let it get you down. There are so many people in the world. At least one other is bound to think your poem's also worth a 10.
But, you know, another person thinking your perfect poem's no good can be seen as a good thing. You could ask that person to show you what they consider to be an example of a perfect poem. Different ideas and values help the world grow. Differing opinions make the world diverse and beautiful.
Don't let fear of disapproval hold you back. Look at celebrities. There are always people out there who don't like them. They're criticized constantly. But because they're strong enough to take it, they've been rewarded.
I think knowing that not everyone will like you or the things you do will save you a lot of disappointment - or at least help you be prepared for it.
Eek. This post's not that clear. What I'm trying to say is that people won't always like you or your poems. There won't always be a lot you can do about it. And, unfortunately, it can hurt. But remember that you're not the only one. I'm sure the same thing happens to those that dislike you. I'm sure it happens to everyone.