dramamama611 said: "^This. (And I wonder how exaggerated it might be, but I'm not through with the book)"
I'm not finished either but there is some dramatization involved for purposes of the show. For example, she was actually married when they met. But they did write letters extensively and, as reflected in the show, she kept in touch with him on politics. Since not a lot was documented about the women from that time, it's hard to know much of what really happened beyond what was left in letters and such.
In the book, Chernow also goes into much more detail on his relationship with the men--particularly Laurens and to a lesser extent Lafayette. His letters to Laurens were particularly emotional, and Chernow questions whether it was just due to the writing style at the time or something more in their relationship. In fact, in one of the letters his family posthumously scratched out part of the letter with the annotation "we can't publish this" or something similar. (I don't remember the exact phrase and I can't find it in the book right now.)
The bottom line is no one really knows what any of these relationships were because the only record of jt is letters. I highly recommend anyone interested read the Chernow book. It's taking me awhile to get through it but it's quite fascinating. Although now when I read it I picture the stars of Hamilton. :)