This is one of the most realistic scenes depicting reasons to have an affair that I ever read.
"The you who loves me is the one I love"
"The reason my heart flutters is because you aren't a part of my "Life."
These here are probably the main reasons that people in decent relationships have affairs.
Some of them turn their lives upside down only to find out later that the "new relationship energy" doesn't last forever and sharing a life is mostly about facing problems together and hearing the other f*t in the toilet.