Hi,
If these birds are in the same cage, then there isn’t much you can do. Cockatiels only have one mate or companion as adults, and it sounds like she is at least his companion. He has no incentive to be tame with you. If she continues to be tame with you, he might come around some. But the best thing to do is talk to him without trying to handle him. If he is going to come around, it will only be if he trusts you, and if you grab at him or keep trying to get your hand near him, he will continue to feel threatened. One concern is that he may become jealous if you handling her. If he ever starts showing aggression towards her, you will have to split them up or stop handling her. I’ll give you the links to our behavior and training pages, and those will help you better understand what he does and why, and how you might get through to him.
Pet Bird and Parrot Behavior
Teaching Your Bird
Thank you for asking Lafeber,
Brenda