Unfortunately, there's always three sides to the story....his, hers and the truth.
We all think that we know everything (because we are family/friends/coworkers), but we usually only know what someone wants us to know.
Who knows what type of relationship these two really had. Heck, while he was in Vegas, she could have been calling like the girl in The Hangover (just used it as an example

) The point is that
sometimes there are things going on that outsiders aren't aware of.
A good friend was engaged years ago. I always knew that she was prima donna (but loved her anyway

). Everyone else thought that she walked on water. During her engagement, her fiance told her that he thought that they shouldn't get maried (for whatever reason, I'm not sure). My friend had one of her other friends speak with him and convinced him to change his mind and continue on with the plans. They married and during that first year, she was asked how married life was. She said "All i wanted was the big ring, the big wedding and the big house"

Needless to say, he left her right after their first anniversary. She came home to a for sale sign on their lawn
My point is that relationships can appear one way to outsiders, but be entirely different behind closed doors. If he had been having reservations about the marriage, and telling her about it, then calling her on the phone may have been better for him (he may have felt less pressured to change his mind if he wasn't right there with her in person).
Just another way to look at things.