In The Great Gatsby, Jay Gatsby believes that one can recapture or recreate the past. Nick concludes his story with an echo of Gatsby's belief:
So we beat on, boats against the current, borne back ceaselessly into the past.
That's what the novel's about: Gatsby's attempt to recreate the past, his past with Daisy. He insists verbally to Nick that one can go back, and his actions demonstrate his belief. He idealizes his brief relationship with Daisy that occurred five years before the novel's present, and seeks to recapture those moments. Of course, he is doomed from the beginning, since the relationship was never as he perceived it in the first place.
Gatsby thinks that time doesn't necessarily change things. He thinks he can pick up with Daisy right where he left off. However, this is never true. Their circumstances prove it because Daisy is married and has a child, this proves toublesome to their attempt to have a relationship together.
Both Tom and Wilson figure out about the same time that their women or wives are cheating on them. Ironically, Wilson's wife is cheating on him with a man well-known to him and he never figures it out, he takes his mystery to the grave with him. Tom learns about it while and for his own good... he was cheating on his wife first!
In The Great Gatsby, Gatsby's attitude towards time is one of desperation. He is desperately trying to recapture the past; specifically, his lost opportunity to marry Daisy Buchanan. As such, everything that Gatsby does, like throwing lavish parties, is designed with this purpose in mind: he wants to gain Daisy's attention so that the pair can rekindle their former romance. In Chapter Six, Nick tells Gatsby that this task is impossible, but Gatsby's response demonstrates both his sense of desperation and his firm commitment to winning Daisy back:
“Can’t repeat the past?” he cried incredulously. “Why of course you can!”
For Gatsby, then, time is also a motivating factor since he believes that his task is not an impossible one.
With regards to the second question, Tom and Wilson both learn that their wives are having an affair. Tom learns that his wife, Daisy, is having an affair with Gatsby, while Wilson learns that his wife, Myrtle, is having an affair with Tom.