He meets them pretty quickly; he walk in on the shower of one of them when he finds that Connie has moved to the English basement to accommodate all the tenants and for their convenience--the upper floors all have the nice rooms and, after all, they can fix things up. The tenants include the usual lower middle class families, widows, and "kravitzers," all with issues, but take more of an interest in things when Jim comes home. For him, his first hours home are a "boot camp" of things that can go wrong, like that chandelier he keeps bumping his head on, and the entryways that are just a little too low. Civilian life will be painful and take some getting used to.
That's why you have friends, like Ed (Jack Paar--yup, that Jack Paar), who barges in on their reunion night with a bottle of champagne, a welcome home present for Jim (a hammock), and a little too much unwanted attention to Connie for Jim's comfort. That's the thing about this apartment building--everybody is in some sort of love confluence, or pining for it. It makes things...complicated.
Take Bobbie Stevens--when an apartment upstairs goes empty, Jim is only too happy to offer it to his "old Army buddy" (as he tells Connie). But, when Bobbie shows up, it's in the form of Marilyn Monroe (take note, if you're watching just for her, she doesn't show up until 33 minutes into the movie), much to Connie's suspicions, and her name is actually Roberta, former WAC. Jim's been tasked with repainting the place to spruce it up, but with all the PG shenanigans going on, the only appropriate color would be green. It turns a darker shade when Ed takes an interest in Bobbie, and her apartment seems to become the party center of the address.
Then, there's kindly Mr. Patterson (Frank Fay)--call him "Charley"--who takes an apartment, pays with cash that he produces from a wad of bills, and who takes unexpected business trips that he's a little vague about...but he comes home flush with cash, and renews his interest in the local ladies who find him gentlemanly in the "old school" way and not entirely unattractive. Everybody likes "Charley"...except when Connie and Jim go out for an anniversary dinner and find Charley at the same restaurant dancing with another woman...when he's said that he's out of town on a business venture. Seems Charley is a lothario making his living fleecing lonely widows out of spending money.
Love Nest was written by I.A.L. Diamond, who'd done quite a few screenplays, but was about to have his closest partnership with Billy Wilder--they'd be collaborating on Love in the Afternoon (released in 1957) and work non-stop until the end of their careers. You can tell Diamond's light touch with just a dash of sauciness--his next work would Monkey Business for Howard Hawks (he did a lot of work with Monroe), but with an affectionate wink that never turns salacious (at least until his work with Wilder in the 1960's). Director Joseph Newman keeps everything light and breezy and nobody seems discontented for long, not even when building complications come along and Jim and Connie start actively seeking selling the place.
I was attracted to look at Love Nest for one reason...it was the last film of Frank Fay, who originated the role of Elwood P. Dowd in "Harvey" on Broadway. One can see where Fay might have been successful in the role; his Charley is always generous and affable, but slightly seedy and the way he plays it can't help giving you the feeling that he's hiding something. His Elwood must have certainly been darker than James Stewart's, which might have been one of the reasons that the play was the fourth longest running drama in Broadway history.
One other note: if the title tune "Love Nest" seems familiar to older folks, it's because it was used as the theme song for "The Burns and Allen Show" from 1950 to 1958--it was originally composed in 1920.