Taking people for granted

I know I do it pretty often, also maybe because I'm not good at appreciating people around me. Sometimes I do it to get rid of people whom I dislike but sometimes I do it to get rid of people that I really adore, because I'm too scared to face what may ensue later.
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After chatting with my pub manager, I realise nothing exciting happens around the pub. Oh well, no drunkards, no fights, its far too decent. Then 20 minutes to closing, we heard a woman shout "SHUT UP". She, a customer shouted at her guy friend/boyfriend sitting across the table from her. Then we could see that he was trying to talk to her, but she kept going "SHUT UP" again and again. She was pissed with him, could tell in her face.
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Then the guy went to the bar to pay.. Without waiting for his change, he left. The girl starts shouting for his name and ran after him. He came back into the pub and whispered something to her (since she wouldn't let him speak earlier) and left again. This time she shouts after him. The guy left. For good. She then tried calling him on the phone but he wouldn't answer. She then left in the saddest state.
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Then I wonder.. Did she expect him to be okay after shouting shut up in his face over and over again in public? Did she expect the relationship/friendship to be the same after that. Did she think he was going to continue sitting across from her while not being allowed to talk?
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Why do girls take guys for granted in that sense? Do we expect guys to come begging on their knees after an argument or after we scold them for something they did wrong? If you're angry at a person and you tell them to shut up, and then when they leave, you chase after them... twice.. why?
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I for one when get too comfortable with people, I tend to think that people can handle my crap.. Of course, there are times when I unintentionally do something.. But honestly, said words cannot be taken back, and regretting after saying something is rather worthless. I remember how I blurted the word 'hopeless' at my friend. twice. i called him hopeless. And I thought, "gawd, thats very insulting. why did i even say it". But of course I didn't apologise cause I meant it as a joke. But how wrong I was. Always remember that if you think it was wrong, then it was. and when some statement hurts, people don't forget.
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don't even ask how I ended up calling my friend hopeless. of course he means the world to me and i think he's one of the most fabulous people i know, hence i took it for granted that he would know i was joking when i called him hopeless.
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why do i take people for granted? what's wrong with me?