A heterosexual couple is talking as they walk hand-in-hand on the state of their relationship. While the female continues to ask questions suggesting she feels their relationship has stagnated and is now decaying, the male simply repeats “I love you” as a reply to every statement. In the final panel, he begins to drown out her concerns by saying “I love you” over and over again.
This comic is most likely dark humor reflecting on a persistent theme in XKCD: insecurity of men within classic heterosexual relationships, particularly from the perspective of a woman seeming to “require more” than the man knows how or is prepared to give.