Silly women can say stupid things in the heat of the moment. Adults really should'nt (especially men). It really depends on how complicated the insult is, to say you hate someone is nothing in particular it can be blurted out.
"I don't love you anymore" is a bit more cerebral, I'd consider the facts and your options. You know her better than anyone.
alternatively also saying things that are not necessarily true in order to anger and hurt, or provoke the other person into an argument/response are also common
i dont know but my xwife used to say some very nasty things in the heat of the moment and then blamed it on her hormones or that dreaded time of the month...i find that woman say theses things to get a response...my x allways said she said these things to get me to react...im only surmising but is ur girl maybe feeling a bit unloved? maybe her self esteem is low at min...maybe u shud sit her down an hav a good heart 2 heart wi her and ask her if she does really luv u.....
Yes, We wil say those things. But you need to draw the line. You know if she is saying it because she is mad. She really wants to kick your ass but she can't.