Can pituitary tumors change personality? What if you don't operate?

[Glindan]

My husband has experienced personality changes from time to time over the last 4 years. They started with a day or two about 5 months apart and gradually grew in intensity, frequency and duration. He blamed me for all the problems - memory loss, anger, paranoia, fatigue etc. and threatened to move out. During his good moments he was his normal, loving self. His sex drive slowed down - I attributed it to the fatigue - but not so much that it was a problem. Between Thanksgiving and Christmas he spiraled downhill noticeably enough for friends to see. After a confrontation with my son in which he threatened him and then screaming in my mother's face, he decided to move out. He said he needed some space, had no intention of filing for divorce and wanted to continue to see each other, hang out, maintain contact. Shortly after he moved out he discovered he had a hormone imbalance and cut off all contact with everyone except his daughter and colleagues - but only at work. (She is maintaining contact with me and keeping me up to date on the situation.) He has since been verbally abusive to me via email and the one time we ran into each other and has twice now says he is filing for divorce at his first opportunity. As a precaution the doctor did a CT scan and discovered a 2 centimeter tumor on his pituitary gland. He started on HRT about 3 weeks after that. He has waited an additional two months to talk with an endocrinologist and neurosurgeon. He is not a candidate for nasal cavity surgery and is refusing to do surgery for at least a year - until his daughter turns 18.

Is the tumor the likely cause of these drastic personality changes? What will happen if he postpones surgery for a year?  If they do the surgery, is it possible that he will return to his normal self?

I do not have any specifics on the location except that he told his daughter that they can't do radiation because of its proximity to the memory centers. The doctors also said it is slow-growing and there is a 99% chance is it benign.

[rumpled]

Yes the tumor can. And until he is treated he will not feel better.
He needs a very skilled surgeon and a great endo to get him on track with replacements. He should not postpone surgery. Odds are the tumor is a fast grower since it is big and the docs he is working with should know that.