Until Ilsa comes into the picture, Rick isn’t motivated by anything. He isn’t driven by money or girls or acquaintances. He found a place full of people whose lives have been broken as his has. It’s unclear what he wants or what drives him; however, we have no indication that he wants it any other way. He’s seems content with the way his life is, ordered and controlled. Ilsa brings memories of a different time; she’s a source of nostalgia of a better, more innocent time in his life. In the end, Rick lets Ilsa goes because he understands that his life with Ilsa was in a different time and place that could never be regained. Their relationship would never be what it was in Paris so he instead goes back to life as he knows it where he is in control and responsible to nobody, except now he wants to start again anew where he can erase any reminders.
Although this analysis completely ignores the macrocosm represented in the movie, it makes Rick seem more real. When looking from the ideal scenario which Hollywood may have intended, the plot and characters become cliché and ideal, many real aspects are taken away as all the characters decide to give their lives to the greater good which is fighting the Nazi’s. If a man were truly in love with a woman and believed she were in love with him, they would not have give one another up. Love is the most important emotion there is and if it were real they would have done anything for it because, ultimately, people are driven by personal incentives over the community good.