Re: Excluded from life at work
There are some people, men and women, who cannot mix their work life with their personal lives. You shouldn't panic unless her push-back to your inquiries is really violent, and then you probably need to do some sleuthing. I do agree it is weird that she doesn't want you coming to parties that are open to spouses. In and of itself it is not proof she is cheating, but it is cause for concern and you should ask her about her reasons why she doesn't want you there.
I did know one coworker who hated bringing her husband to office parties, and I never understood why until he did come to one. Simply put: this guy was a jerk. He was an opinionated, pompous boor who managed to insult or irritate just about everyone at the party within the first hour he was there.