Hard to really appreciate a book when the characters irritate you, the plot is contrived and frankly, you don't give a damn.
Heroine... family doormat and borderline TSTL. She watched this guy pursue her beautiful model cousin, then when he gave up and went after *her*, instead of maybe being a lot hesitant at being the consolation prize, she...got engaged. A message at work said for her to check on her cousin, whereupon she finds the two of them going at it. She staggers back to work, gets plastered on coffee and brandy (coffee? In the UK?), and eventually passes out in the H's limo. She wakes in a night gown, and instead of wigging out, she presses him to pop her cherry (doesn't tell him that part - he finds it out) Over the next couple of months... she's pressed into marrying him (didn't resist v. hard), has to deal with his bipolar attitude toward her, has a meltdown and pretends to leave, meets the ex for a counseling session, deals with more of his douche-y behavior, meets yet another ex of his (yeah, she was practically tripping over them). And HEA supposedly...or until he has another temper tantrum.
Hero - stalker creepazoid who sicced a PI on her then-fiance in hopes of finding dirt on him - spent 2 months acting like a spoiled brat because the h actually objected to his manipulating her to get her in his clutches.
Cousin - spoiled heifer whose parents indulged her to make up for her being jealous of the h's friends (h was a nice doormat sort, of course she had friends)
Aunt/uncle - resented the cross they had to bear and also resented that said cross landed the douche...while their precious brat had to settle for the dumbass who'd wasted time pursuing her earlier.