Love is not the answer to meaninglessness
The primary marriages shown in the book are Nick and Marian Shay and perhaps also the failed marriage of Manx Martin who steals the winning home-run ball from the "Shot heard around the world" from the novel's introductory short story (also released as Pafko at the Wall).
The argument against Nick and Marian's marriage is that both of them have a more meaningful affair during the course of the book, and each of them return to their marriage not because they believe it will yield more meaning, but rather because they have already sufficed their need for meaning.
Transcendentalism as an underlying element of life
DeLillo's short story and opening to this novel, Pafko at the Wall, is referred to as his most transcendental piece by some critiques, which is saying a lot given his highly spiritualistic oeuvre.
The intro's transcendentalism comes through thematically because of it's underlying nature in the baseball story. Because of the very human element of the occasion and also the important world-political issues in the ballgame, the effect of the story ends up being that more is happening than could ever be understood or suggested.
Drug usage as the byproduct of existentialism
Existentialism is the belief that human life has no meaning except what the humans decide to invest into it. In the novel, the affair of the main character's wife (Marian) includes explicit heroin usage. This drug usage is not condemned as it might have been in more modernistic views. The drug usage seems to be a narrative byproduct of the meaninglessness of the drug usage itself, thus leading to the casual tone surrounding the otherwise-severe drug usage.
