Bridesmaids, now that I think of it.
And here I was thinking they were about the Lady of the house having an affair with the stable boy…
I’m pretty sure Indecent Proposal fits.
This seems to have been a popular trope in the 1930’s, where the woman comes from money but the man doesn’t. I forget the names of all of them, but The Thin Man and My Man Godfrey come to mind.
Picnic
ISTR it had involved Aunt March’s help.
Robin Hood? Breathless? The Graduate?
Fiddler on the Roof?
Not sure if it counts as a chick flick, but I remember as a young girl, how happy I was that Tzeitel got to marry Motel instead of being forced to marry Lazar Wolf. The part when Motel is sings “Miracle of Miracles” is pretty romantic.
The first two girls that are old enough to marry get a poor tailor, and a poor student. Poor Tevye. 
Reality Bites
Thought for sure someone would have mentioned this one: Sweet Home Alabama. She gets married to a poor guy, then runs off to New York and reinvents herself as a big-city socialite. She gets engaged to a high-society type, but she can’t marry him until her first husband agrees to a divorce. So she goes back to Hooterville and, of course, ends up falling for the first husband all over again. At the end her New York fiancee turns out to be a total doormat, incidentally, and doesn’t put up a fight at all over losing his bride.
Didn’t Pretty in Pink rather famously get a rewrite so that the poor guy won?
I always thought this was an example of poor writing:
Rich guy: What if I gave you 1 million dollars to sleep with your wife?
MY IMPROVED ANSWER: Great! What’s in it for her?
While You Were Sleeping. It starts with Sandra Bullock lusting over Peter Gallagher’s rich, handsome, successful bastard character, but she ends up with his brother, played by Bill Pullman, who’s blue collar.
Other way around. In the first draft, she was supposed to choose the guy who had never let her down. They changed it to Duckie martyring himself because reasons.
Oh, that’s right, they were officially worried about “class issues.” My bad.
“Would you sleep with Robert Redford for a million dollars?”
“Sure, but I don’t have a million dollars.”