"Well!" he said. "Well. How does it feel to be an old married lady?"
"Oh, it's too soon to ask me that," she said. "At least—I mean. Well, I mean, goodness, we've only been married about three hours, haven't we?" (11-12)
Their marriage is in a state of total uncertainty right now. It's unclear how it will work out—though the story might give some hints.
"All mixed up, and then thinking of all those people all over everywhere, and then being sort of 'way off here with you. It's so sort of different. It's sort of such a big thing. You can't blame a person for thinking, can you? Yes, don't let's ever, ever fight. We won't be like a whole lot of them. We won't fight or be nasty or anything. Will we?"
"You bet your life we won't." (43-44)
This is totally ironic given that the husband and wife have nothing but petty arguments less than three hours after getting married.
"Here I've sat and sat, and just listened to you saying how wonderful Louise is. I suppose that's nice, getting me all off here alone with you, and then raving about Louise right in front of my face. Why didn't you ask her to marry you? I'm sure she would have jumped at the chance. There aren't so many people asking her to marry them. It's too bad you didn't marry her. I'm sure you'd have been much happier." (55)
The wife feels vulnerable and insecure being stuck with her husband, alone, away from her family. She evidently feels at the mercy of his whims and attachments, and wants to make sure that he has her best interests at heart—which is why she's accusing him of having a thing for Louise.
"We used to squabble a lot when we were going together and then engaged and everything, but I thought everything would be so different as soon as you were married. And now I feel so sort of strange and everything. I feel so sort of alone." (75)
All the wife's sources of security—her family and so on—have been stripped away, and now she has to face the totally new situation of living with her husband. This is probably the source of her feeling of loneliness—her vulnerability and exposure. If you don't really understand the person you're married to, it can feel like you're in the marriage alone (of course, they haven't been married for three hours, yet, so this is probably a premature reaction).
"Well, you see, sweetheart," he said, "we're not really married yet. I mean. I mean—well, things will be different afterwards. Oh, hell. I mean, we haven't been married very long." (76)
By "we're not really married yet" the husband means that they haven't consummated it yet—in case that wasn't clear. Also, we can't be sure if we believe his assurances that everything will be different afterwards—and neither can the wife, since this is the very thing that seems to be making her nervous.
"And we won't ever fight any more, will we?" he said.
"Oh, no," she said. "Not ever! I don't know what made me do like that. It all got so sort of funny, sort of like a nightmare, the way I got thinking of all those people getting married all the time; and so many of them, everything spoils on account of fighting and everything. I got all mixed up thinking about them. Oh, I don't want to be like them. But we won't be, will we?" (98-99)
The wife's question remains unanswered by the time the story ends. Will they be okay? The story has some ominous signs, but the years are the only thing that can reveal the real truth about their marriage.
"We won't go all to pieces," she said. "We won't fight. It'll all be different, now we're married. It'll all be lovely." (101)
This might just be wishful thinking, considering that they've fought throughout this entire story. That might get old after awhile.