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.