Prejudice Against Homosexuality
George is a man born in the wrong era, forced to hide his true self for fear of arrest and incarceration. Growing up in 1930s Britain he was forced to live a double life, pretending to be a straight man when in fact he was living an underground life of illegal illicit relationships. Relocations to California, he finds his homosexuality less illegal but equally frowned upon and rejected by the majority of society. Throughout the book, we see that it was an everyday occurrence for gay men to be discriminated against and even despised. For example, Jim's parents don't care that he made their son happy. They only care that the appearance of their son being a straight man is upheld and don't recognize George as his partner, even choosing not to invite him to Jim's funeral.
Isolation and Loneliness
George is the single man, but is really the lonely man. Outside of Jim he had no real relationships that meant anything to him. He is isolated because of his sexuality and also because of the need to mask it with a veneer of acceptability. Because he has to constantly hide who he really is George is isolated from himself as well which just exacerbates his loneliness. Charley is also a lonely character as she is passionately in love with and apparently saving herself do a man for whom she can never be "the one" because she is a woman and therefore undesirable to him.
Grief
George is suicidal because of the extreme grief he is experiencing after losing Jim. This grief is heightened because he was not able to grieve publicly or to have any kind of closure on his relationship. Throughout the novel it is clear that all he thinks about is Jim and that his suicide is not so much a result of depression but a result of grief and the fact that he would rather be dead and be with Jim than live where Jim is not. The separation between grief and depression is key to understanding George's plan to kill himself.
