For all that it's an enjoyable read, it does have issues.
It's a cheating book. The h is the H's best friend's betrothed.
It actually takes place over less than a week, although you don't realize that.
The H - and his friends - appear to be idiots, or at least, irresponsible dolts.
So the h, for whatever reason, agreed to marry the H's best friend. The wedding is in a few minutes, and she's in a state of panic, because she realizes she does NOT want to tie herself to a man-child just to help her family's finances. She imbibes a bit of liquid courage, and climbs out a window. The H, sent to see what's taking her so long (think Princess Druidia from Spaceballs) sees her running and gives chase.
Chasing proves to be more involved than just running her to ground as she's determined, bossy, and he's only ever dealt with one bossy female before - an aunt we meet later. So much of the book happens in less than 24 hours - being trapped in some sort of conveyance with her, rescuing her from a dipping in the Thames, finding out her aunt has flown the coup (her intended destination), visiting with his aunt...
She spends a lot of time prior to sobering up ranting to herself (he's mostly to provide a voice to the answers really...). He spends a lot of time figuring out how to dawdle in hopes the groom will catch up.
And the groom spends a lot of time drunk, which was possibly one of the reasons she suddenly balked.
Eventually she decides that the H is not going to do the dishonorable thing without a lot of incentive so, while they're seeking shelter in a thunderstorm, partially disrobes and well, men apparently lose their minds at the sight of ladies' underthings.
I am guessing the next one is his friend and his sister as they're married but not exactly enjoying a happily ever after.