If he is stressed, don’t cause more by asking what the problem is. The worst thing you can do is ask him what the problem is and not leave him alone until he opens up. The more you press by asking what is wrong, the more he will pull away. Let him have alone time to work a solution. Once he comes to a resolution on his own, he will bounce back with love, support and attention.
If he is bored in the relationship, then he is emotionally distancing himself from you. Ask him if there is something you are or aren’t doing. Once he tells you the cause of the boredom, you can decide whether you want to fix it.
He may feel suffocated and feel the need for freedom. He may feel that you are getting too clingy and that he needs to spend more time with his friends. He wants his independence again. He needs to be able to do what he wants when he wants to do it. If he feels like he is chained to you, he is going to emotionally distance himself from you and finally break away.
Men like to avoid conflict if they can. They clam up to prevent an argument if possible. If you are the type of girls who explodes at the drop of a dime, it might be time to rethink your approach. After all, just that may be the cause of his distance.