Bucky is still technically dead to the world, so there's a reason he wouldn't come up in normal conversation, and I don't think it's very hard to handwave some kind of explanation where, at least temporarily, she couldn't even make new memories of him. After all, her question upon his rescue was "who the hell is Bucky?" She did, obviously, see him in the hospital. And mindwiping is weird.
For me, I don't need the actual nitty-gritty details about how this mindwipe worked, just a working status quo going forward. (One that hopefully I don't hate, fingers crossed.)
On a nice, non-Bucky topic, I like the fact that the second arc of her series is focusing some on the superhero connections she has. It's a nice counterpoint with the first arc, which has been wisely spent building up Natasha's own little world. Natasha may have spent some action scenes in issue #4 inner monologuing about how she's not Tony Stark, Steve Rogers, &c, but she is very much an Avenger, a superhero, and it's fun to explore how and if she balances that. I'm glad to see her team up with Matt, since that has been a while in coming, and ditto with the upcoming WS issue, but I hope not everything will be a tour of the ex-boyfriend gallery. I think she's kind of done a disservice her exes are the only significant connections comics remember, y'know? I hope for a Spider-Woman issue, maybe, since Jess and Natasha have become closer recently in Avengers books and she'd really suit the tone. Or maybe Noto would like to draw X-23 again? That was the arc Marjorie Liu was beginning to tell when X-23 got cancelled, it would be neat to see that thread being picked up.