Yes, this 'new' Mat is becoming like a 'rockstar'.
But let's take a look at Patti now.
I disagree with your statement that she was from a poor family - poor people always get degrees from universities (if they can) in something like accounting, engineering (computer science) or medicine (if one is really smart). In other words,
they need money to enjoy life a little bit (they are simply too tired of living from one paycheck till the next paycheck).
But Patti got her degree in
art (which can be seen from her high quality realistic paintings) - money was not a priority for her (I am guessing, a middle class family). When she was studing at the University she met Mat - tall and good looking guy with a steady future job (which was a good choice for her - so she can continue her art work without worring too much about paying the bills).
And then (as you correctly pointed out - '
boring routine'). Mat comes home after work and he is a bit tired, so nothing special in the evening - a simple diner in front of a TV (or watching sports on TV) and occasional going out for food/drinks.
Technically there is nothing wrong with this
good and stable life, BUT this is not 1980s anymore - now we have 'Instagram'

and other 'amazing' social networks (which have plenty other people bragging about their 'successful life' - expensive cars and yachts, holidays, travel, etc).
Patti feels like she is
slowly drowning (her life is moving nowhere) - her paintings/works are sitting home while Mat is busy/tired with his job.
In general, people who do art (painting, sculpture, etc,
but not music - like pop-songs) are more interested in 'leaving the mark' in the society/history -
FAME is their main hope/priority.
And then Patti meets Chris - who is older, but well mannered, well spoken, who knows things about art and politics
and has good connections in the
high society (
plus he can arrange an Art Exhibition of Patti's work 
).
This is exactly
the glamorous life, that Patti was dreaming about!
So can we really blame her for leaving Mat and persuing her
real dreams?
PS. Maybe next time we can take a look at Chris and some other
interesting people.