I'll explain this movie for you...

Rating: 10/10 (2 April 2017)

I am amazed by the amount of people calling this movie a boring and insane film. Actually, this sums up one of the things the thriller talks about us being slow brains and dumb. I think that must be the case of the majority happy people who don't need to have his/her gears working too hard. Life is simple, huh.
This contain strong spoilers, but this is for those who did not understand the movie and genuinely want to.
THE "FLASHBACKS". ----------------- The apparent flashbacks you see in the beginning of the movie are neither flashbacks nor flash-forwards she's having at that moment. The movie just shows you the future and tricks you into thinking she is thinking about her past. But those thoughts and her are still disconnected. Only the watcher will see that there is this connection and the watcher places this events in the past, as the movies intends to. In the now, she does not give any clue about mourning. She doesn't seem very happy at into the now, but actually it has nothing to do with the future yet.
WHO IS THIS GIRL I KEEP SEEING? ------------------------------- By the middle of the film, you notice that as soon she is into the mission and approaching the Aliens, she is starting to feel weird and have the flashes. She is opened up to communicate, and she then start to have the actual flash-forwards, because the aliens start this process. Up to this point, the "flash-backs" we were tricked into thinking they were this, were not happening to her. But now they start. And it gets stronger inside her while mission carries on. When she definitely meets the alien inside its dome, she now is given a gift to see the future. She uses that future information to give humanity a fate in that particular situation (with Chinese leader) and she knows fully now that the girl is her future child that will die from cancer.
MARRIAGE FALLING APART ---------------------- She learns within the process of knowing the future, that her husband will leave her, because she will reveal too soon that the child is going to die from cancer. The guy, apparently a strongly firm steady and centered guy in the action, is actually a emotionally fragile and weak parent. With her passing the knowledge to him that she will eventually die, he can't cope it with the reality, and leaves the family when the girl is around 7 years old. (Although we have seen that the girl will actually die in her late teen years). So the husband, the guy, doesn't accept the loss, and moves on selfishly - even when the event is already years ahead. A weak and emotional broken party.
HER EMBRACING OF THE FACTS -------------------------- So when the aliens go away, Dr. Louise is now fully aware of the future. That she will have written a best selling book, that she will have worldly recognition of her work. But she ultimately makes a choice: She will not change anything. She has loved the child already, she know the girl will have cancer, she accepts it. She doesn't prevent anything from happening. The only part that we are not told is that, when she makes a decision to inform her now husband that she knows the future and the child will die, it is considered a mistake she have had done, but certainly she doesn't know yet on how this will develop - thus it will be a "mistake" on her part. Nevertheless, she won't change anything. Also, she is not aware of 100% of things in the future (that is why she makes this single mistake).
This movie is about love and loss and human beings. It has nothing to do with aliens that much. It's a movie that will help us understand how tiny and insignificant our mediocre lives are, and what we think is under our control, it is actually not.
This movie is on par with Butterfly Effect (1) and Inception. Interstellar breaks too many physics rules to be considered a better movie, but Interstellar is in fact much of a block buster, with massive physics mistakes (there is no way one can survive being sucked by an even-horizon).
Well, I hope you reconsider this film. Watch again and see what a masterpiece it is. Get your gears going faster and you will understand.
Cheers.