Mark and Emma, longtime unmarried partners and parents of seven-year-old son Sam, decide to wed despite the growing rockiness in their relationship. Mark's brother Rich is part of the problem: Rich and Emma secretly long for one another, unbeknownst to Mark and to Rich's girlfriend Louise.
As Emma and Mark arrive back from their argumentative honeymoon, best friends Amanda and Michael decide it's their turn to find love: but while romance is just around the corner for Michael, Amanda discovers that her combative attitude fails to attract Cupid's arrow.
Rich and Louise struggle to cope with the reality of Louise's mother Donna's illness, and turn to Emma for advice and support, which stirs up memories of Emma's own pain when her own mother fell victim to cancer.
Worried that Emma is being unfaithful, Mark tries to improve their relationship and social life by inviting a colleague and his wife to dinner, but the evening does not go according to plan. Sinead realises her love for Mark will remain unrequited and arranges a blind date via the Internet in the hope of meeting the man of her dreams.
After making a pact with Louise to find a new job, Emma finds herself being interviewed for a teaching post by an old college friend, and Sam is none too keen on being babysat by an uncharacteristically broody Amanda.
Rich is unable to shut Emma out of his mind and takes drastic action by proposing marriage to Louise. Mark is involved in a serious accident, which also gives a jolt of sorts to Emma and Rich.
Michael's life is thrown into turmoil as the police arrive on his doorstep demanding to know what went on with his date. Mark finally discovers who gave Emma the lovebite on her wedding day.
It's been three months since Mark walked out on Emma, but everyone is still reeling from his actions. Emma and Rich haven't spoken since their near-affair set the entire drama in motion, while the rest of the group are either pointing the finger of blame or ignoring each other. So, when Louise organises a 32nd birthday party for Rich, it seems the ideal opportunity for some long-overdue hatchet-burying.
Emma is determined to date Amanda's dishy friend James, despite cautionary advice. Louise becomes increasingly broody, but worries that her past might catch up with her and scare Rich away. Sinead returns from her Corsican holiday with an unusual souvenir, in the form of sexy and impulsive soldier Herman, who encourages the Sinead to have some fun.
The men reach crisis point and seek external help with their problems: Expectant father Michael enrols on a course to teach him how to become a real man, while a frighteningly accurate fortune-telling prompts an already anxious Rich to spiral deeper into despair.
Mother-to-be Amanda worries about her newfound nesting instinct, while Louise prepares for her impending nuptials. Meanwhile, a blissful Emma begins to make premature plans for her next wedding. But how long can Emma's happiness last after James embarrasses poor Sinead in front of the gang and delivers shattering news to his lover?
James moves in on Louise, using all he knows to stop her marrying Rich. Michael receives an unwelcome guest who has life-shattering news.
Rich and Louise's wedding day looms, but a heart-to-heart with best friend Emma leaves the bride-to-be with last-minute doubts. Meanwhile, Emma struggles to adjust to life without James, and Sinead has a tough time sustaining her affair with Herman the sexy soldier.