Jess seems lonely and desperate: after many years of trying to survive in the world on his own (which, in a material sense, he succeeded in doing), he’s come back home. The farmland isn’t so easy to escape: even if Jess isn’t financially dependent on his father, farming is in his blood. Ginny has clearly been attracted to Jess for a while, and this kiss begins the more dramatic action of the novel. (It also once again parallels
King Lear, in which Edmund has an affair with both Goneril and Regan.)