Geralt was young at some point too. There are many things you can do with long hair... imitate Korean from 500 years ago or sth... but it all doesn't matter.
Looks gives very little or no relevance to most of things. Your mental approach is what matters. If long hair suits you, wear them.
The longer you live, the more things you will notice to be irrelevant, and not worthy paying attention to. Within some range, that you don't look inappropriate for the situation, disgusting or scary, any style is good as long as it's ok with you.