If we look at this movie through today's eyes (SPOILERS)...
...What does it tell us , class ?
It tells us that , a " barely legal " (I guess) naive small-town HS graduate should run off and get married to a trainhopping homeless alcoholic veteran to go somewhere else entirely , that's what ! And I won't even cover the sub-plot about Rosalind Russell's character for now...
NOTE: I haven't seen the movie real recently , and I've never seen nor read the play ~ Which , especially considering the censorship standards then , may have been a little " nicened " up for H'Wood , I suppose .
Now , it is somewhere between 1952 (the play was produced on B'Way in the 1952-3 season) and 1955 (Who are the pop/movie star pinups I think I see next to Kim's bead of , by the way ?) . I will presume that Novak's character is a this-year HS graduate , 17 or 18 , and rural Kansas's age of consent is probably around that , I suppose . Strasberg's character , with her ambitions of going to NYC and being an actress , is rather more sophisticated .
Even if Holden's character was a WWII veteran having lied himself into the Army at 16 , that would make him 21 or 22 in even 1952 at the earlies ~ And (the issue about Holden's actual age left aside) - he is probably older than that .
He is homeless , has hopped a freight to get there ~ I believe he is shown drinking , and conventional wisdom today (Which I don't nessecarily agree with , just as with the other present-day c. w. I invoke here , but I believe it would exist that way today) would tend to hold that a hmeless person who drinks is by definition an alkie .
He has been a drifter ~ Would he be considered to be a PTSD case ?
He wants naive Kim to go join him in a cheap room somewhere ~ The modern-day " correct " mental health advisors , among the lines of Oprah/Suze Ornman/Dr. Phil , say , would almost certainly respond to this with " NO NO , NO , GIRLFRIEND ! HE'S SICK , AND PROBABLY A LIKELY ABUSER ! YOU DESERVE MORE ! " !
They would tell HER to go take night courses and do volunteer work ~ And Holden , they'd no doubt recommend for a locked rehab program (of which there were considerably less back then) , with Kim to , POSSIBLY , visit him on Veterans' and Memorial Days and hand him a baked cupcake and say " Thanks for your service " . That's all !
Let's return to the age differences , too . I think we can agree that Inge was picturing a man of at least 25 or so ~ going out with ~ and planning to marry , on maybe two days' acquaintance , a pretty naive HS grad ~ Our attitudes about " age-appropriate relationships " have rather changed in 65 or so years , I'll say that !
MAYBE it would be " barely legal " to-day ~ Or , possibly the Holden character would be up for a felony rap , prison time , and sex offender status !, depending in part on the local DA's inclination ! These romance between under-18 females and over-21 males happen quite often in Golden Age Hollywood films...