"the number of texts I have received from my husband during our five years together can be counted on one hand, I know it?s utterly unlikely he?ll be sending text messages to anyone else"
yeah love... course it is...
Although she is so vain that I doubt she thinks her husband would even look at another woman anyway, not when he is married to the stunning vision of beauty that is her... 
Too vain to realise that someone is likely to do it, just for the fun of pissing her off because of her arrogant attitude.
Incidentally, I have been married to my husband for ten years, and never felt the need to rifle through his phone or his email, nor him mine. I have on occasion had to look in his phone at his request for something, if he has left his phone at home maybe.
I would say if you are in a relationship where there is no trust, there is no relationship.