The term or phrase "I see how it is" is referred to or can be translated as "I understand how it is" or "I have seen or released something as a fact. It can be used to anyone but normally to someone who you either know or have a conversation with where the say something or do something which you didn't expect.
"I see how it is" is also used in very complicated situations where you think you have worked it out.
It can and is often used sarcastically between friends or as a joke way.
It is often also a word to say how a relationship has broke down or trust or most likely loyalty to one another.
"I see how it is" is also used when someone thinks you don't know something but you don't want to say so you hint it to them
For example, Mr Smith says to Mr Hill, remember the time when I sorted that general thing for you pretending to be helpful in return for that favor you did for me. Well, I only did it to get information out of you and now you owe me? Mr Hill, well that's very mean of you now isn't it, I was suspicious u did it for that reason even though you was returning the favor but I thought you was a good person and not a snake. Mr Smith says Dog eat dog world and by way I need you to sort this out for me or I will make things difficult for you and now you owe me. Mr Hill says "I see how it is"
Another example Mick and Mack are close friends in a bar, they see two very attractive girl looking at them and get signals from her and Mick is sure she is looking at him.Mick says to Mack, She looks good and I think, I am going to go chat to her. Mick pops to to the toilet. When Mick gets back Mack has already driven her away by telling her some bad jokes about Mick. Mick tells Mack and Mack laughs and says well thanks for messing it up for me lol. I see how it is.
For example between family, friends or relationships where trust or loyalty is broken down, the person who feels let down says "I see how it is"