Deceit
Many of the characters in the novel -- including Eric and Alison -- engage in deceitful acts. These acts are typically directed towards other people as a means to benefit oneself. However, in some cases, people in engaged in acts of self-deceit. That is the case in The Land in Winter. Characters like Eric, Irene, Alison, Bill, and Rita all live in the West Country. They claim to like their lives, but continually sabotage themselves and those around them by cheating, stealing, and engaging in other nefarious activity. All of the characters want a way out of their lives and the place they live, but lie and deceive themselves. After all, their indications show that they're not happy.
Separately, Eric cheats on his wife with one of his patients, Alison. In doing so, he is deceiving his wife and betraying the idea that he is a happy family man. These acts of deceit show that to live a happy and harmonious life, one should never lie to themselves.
Boredom and Isolation
Living in the West Country, far from significant numbers of people, resources, or other culture, has made people isolated and bored. They spend most of their time with their family. One of their community touchstones is the Boxing Day party, when all neighbors across hundreds of miles gather together to celebrate. But that's only once per year. The rest of the time, they're left largely alone, causing them to grow bored and leading them to trouble. Isolation, in other words, can be supremely damaging to a person's psyche. It has also led to the major conflicts in the novel.
