Most Helpful Guy
Why not? The worst he can say is nothing.
Most Helpful Girl
There's such a stigma attached to an ex. But honestly? Follow your heart. If it's what you want to do, then do it. It's the way that you do it that will matter.
Say happy birthday, but that's it. Keep it light, friendly and wish him a lovely day. Say nothing about missing him or wanting him back, especially if he's distant at the moment. Give him the same amount of attention he's giving you.
If he replies then great :) But don't reply unless he asks you a question or gives you something to talk about. You need to make it clear that you're not going to push him for anything. Focus on making yourself happy and if it doesn't work, know that you deserve the same love in return that you're willing to give to someone else.