Nature and society
Gifford doesn't really like the social world he lives in. He understands he is somewhat privileged, but his participation with society is always awkward and clumsy. He feels that he belongs in nature, where he takes long walks and escapes from the prison of duty and social responsibility that plagues him. When his father dies, it takes him over two decades to marry and carry on his filial duty to the estate. He doesn't want it. The novel ends with him abandoning everything to go live alone in the mountains.
The estate
The imagery of the estate defines the social niceties that happen therein. The formal elegance of Fleetwood's father's estate is a sign of properness and nobles oblige, but Fleetwood struggles to live up to the imagery his home implies. This makes him a likely target for people like Gifford who see through his thin façade and seek to take the estate away from him. The first portion of the novel uses the imagery of the estate as the home base in a journey through Europe; he leaves and returns to the estate, learning on his arrival that he has inherited it.
Marriage and intimacy
This is not a love story that will make people jealous. Fleetwood loves his wife, maybe, but their relationship is not intimate. In fact, they each keep their emotions private, and secretly, Fleetwood thinks that Mary is looking down on him, when sadly, she is looking up to him. As an orphan, she just wants a strong family man who she can trust and count on. Fleetwood isn't that person. Notice that even after Fleetwood's awakening, when Louisa's father clarifies his mistakes, he still leaves his wife. He feels he isn't designed for marriage.
Chaos and thievery
Thievery is the main depiction of chaos in Fleetwood's life. When the chaotic character, Gifford, enters his life, the intention is to misuse Fleetwood's trust to steal his property from him. He does this by convincing Fleetwood that Kenrick is trying to steal his wife. When Fleetwood runs away from home, he is ambushed by a gang of bandits who robs him and leaves him for dead, and when he realizes the truth, he voluntarily gives his possessions away and moves to the Pyrenees to live alone.
