If you don't like Alex's blue hair...

For one thing, he hasn’t even styled it yet. Wait until he does his own thing to it, it’ll look great. 

Also, he’s already self-conscious about how he looks all the time, so it took a lot of courage to dye his hair such a bold color. And he’s clearly spent over a month contemplating whether or not he should do it, and the fact that he did do it means he really wanted it. 

Don’t tell him he looks dumb or that you prefer the brown or whatever. If you’re going to post your negative opinion about it, don’t tag him in the post. Or just don’t say anything at all. That would be the best option.