You aren't mixing anything up, both things really were brought up in this manhwa, it's most likely a writers mistake and a plot misunderstanding
I think in the beginning chapters, she meant that Claude didn't want a wife because she understood it would hurt the women the most if they were off to battle while their wives stayed at home having to worry about their safety all the time. Now, she's confused about why he doesn't want to love someone, rather than just having a wife, perhaps?
Yeah but didn't she explain the reason was because he would hurt the wife and he didn't want that? I'm pretty sure she made it clear the reason was that. I could be wrong but, Oh well. I still find it strange how she suddenly forgot.
I noticed something weird. I think in one of the beginning chapters she mentioned why he doesn't want love. ( Because It'd like bring him down or something I think. I don't remember exactly.) And now in chapter 40 she is confused about it and doesn't know the reason? I'm not exactly sure and I could be thinking of another manwha but I think it was this one. Anyways, I just noticed that and found it weird.