Hermione is a woman who, for the most part, does things deliberately, having thought out what, why and how. That is not to say that she doesn't have emotions, only that she doesn't allow them to drive what she does.
For example, before leaving with Harry and Ron at the beginning of The Deathly Hallows, she goes to rather extreme lengths to prepare in every way that she can. She erases herself from her parents' life, sending them to Australia where they will be safe. She also carefully packs a magically expanded purse with a wide variety of "essentials" including a small library.
When Ron leaves Harry and Hermione, he is ruled by his anger and frustration, and his departure is an act of passion. He later tells Harry that he almost instantly regretted leaving and worked for weeks to find a way to rejoin them.
Hermione understands why Ron acted as he did, but she would never have left with him for two reasons. First, as already mentioned, she rarely if ever, loses control of her actions like Ron did. Second, she understands, unlike Angry Ron, that no matter how much frustration or even anger she might be feeling, Harry is still the best hope for defeating Voldemort. Hermione knows that if Voldemort is not defeated that she and Ron have no real hope of any kind of life together. Her love for Ron, her parents, and her other friends would never allow her to put their mission in jeopardy while any chance of success existed.