One way in which Lennie's and George's relationship affects their lifestyle is that they live for one another. It is clear that both men recognize that their relationship is the basis of how they live their lives. For example, when Lennie gets into trouble in Weed, both men must go into hiding. When Lennie is hunted down by Curley's lynch mob, both men have to act accordingly. In these instances, it is clear that their relationship affects their lifestyle. They cannot live comfortably when the other one is in danger.
Another way their relationship affects their lifestyle is in their continual reliance on one another. This aspect of their relationship becomes an embedded part of their lives. It can be seen in their refrain to one another that "Guys like us" are different than others because they are present for each other. It can also be evident in how they are able to tell others that both of them "go around with one another." This is something received with surprise by people like Slim and Curley. Their relationship affects their lifestyle because the image they project to other people is fundamentally different than what others have seen. In a world where independent despondency permeates all aspects of being, the relationship that Lennie and George share and the lifestyle that goes with it is fundamentally different than what others see and understand.
Thank you this was very helpful!