As I (finally) watched this, my only thought was "well, you wanted to see it".
I had high expectations, which were unlikely to be met, but at the very least I was expecting to enjoy it: I love Claudette Colbert and like Fred MacMurray, the two leads, and I think Mitchell Leisen is one of the most underrated directors of the 1930s and 1940s. The three together produced an unusual 1940s comedy which I liked very much. So how could the follow-up be anything if not entertaining? From that opening line go, you can guess that I wasn't particularly impressed with the film. And not for the reasons that MacMurray mentioned somewhere (that they were too old, which is actually irrelevant for this story). No, the problem is that the premise isn't in the right tone and the plot is badly constructed.
The premise is that a pilot about to embark on a suicide mission says he'll miss Peggy the most in his farewell message. Except he didn't say Peggy (a former co-worker) but Piggy (his dog). This would have worked wonderfully in another context than a suicide mission during WWII and filmed straight (as it should). As he survives, the mistake needs to be upheld to the obvious conclusion. The problem is that we are expected to move from serious (and real) drama to light romance (and back again a few times). This is never an easy change in key and not Norman Krasna (the writer), not Leisen nor the actors manages to do so. And as the key keeps changing, we go from MacMurray's female pursuits to serious war concerns back to romance. You would need a better script, better motivated actors and more inspired director to do it.
If the wrong tone can be ascribed to everyone, Krasna is the sole responsible for the bad plot. Following a clear (and perhaps forced) three-act structure, implausibility sinks in when the two leads, allegedly in love, are never left alone for the whole of Act I. At this stage, the truth comes out and for the sake of war effort, they decide to continue with the deception. The plot is further contrived by the fact that they are "invited" to spend his two week leave in a house of a millionaire who decides he can meddle in other people's affairs and treating them as children (locking a door?!). By the end of Act II there has been way too much fuss about sleeping bags and other nonsense, but there was a decent, even amusing, Act III (with even a dig at twin beds).
The cast is painfully underused. Colbert's part is very one-dimensional, and her performance lacks any spark, only allowing some rather welcome mischief in the last third. This was her last film for Paramount, and by golly, it shows it was an obligation. MacMurray is wrong for the part and probably lacked any interest to do something with it, as around this time he was showing he could actually act in Billy Wilder's "Double Indemnity". And there is a major problem in the architecture of 1940s romantic comedies. The de facto lead was always the woman. A few exceptions apply, as usual. Here the female lead is reduced to a cardboard figure, and MacMurray carries the film through the first hour. Or rather doesn't. Ray Milland, who usually got the not so wholesome leading ladies'
leading men parts at Paramount would have been a better choice. Because the part is less than wholesome for the first two acts, and at times could be a young Sheldrake, his part in Wilder's "The Apartment".
This is the weakest of all Leisen's films I have seen (although I stopped "The Lady is Willing" because I thought it was atrocious) and second weakest of the seven Colbert/MacMurray pairings. I am glad to have seen it - I would have been very frustrated otherwise - but not something I intend to do again.