She still wants the marriage, and she is still hoping you will change your mind.
I agree that this is probably true and, without knowing her, I kind of assume this is what she's doing in her own sort of awkward way. I don't think she's manipulative in an evil genius mastermind sort of way, but more in an anxious-avoidant, passive, can't be direct with her feelings, sort of way. Regardless of her intent however, the effect is manipulative.
I'm not sure what things look like between the two of you at the moment Ink, but she could have come to you and told you how she was feeling (ie. sad, wistful, mourning of the relationship) and asked in a 'no pressure' sort of way, if you'd be willing to join her for dinner to acknowledge the anniversary/grieve the relationship etc. That could lead to a discussion where you might discuss this further and see how she was viewing it and have some potential negotiation or discussion. This, of course, would necessarily involve a level of vulnerability that I assume is outside of her comfort zone - especially if she didn't think you would accept the invitation.
Instead, she avoided a conversation by leaving the note, which meant that not only did she avoid the vulnerability, it left you unable to discuss or negotiate the terms of such a dinner (if it was something you would have considered under any circumstances at all). It put the ball entirely in your court to make the effort or not, to demonstrate the show of vulnerability in the relationship. ("You're welcome to join me" is not the same as "I'd really like it if you were willing to join me...") It's you going to her (again), rather than her coming to you (what I know you had previously been wanting). Perhaps she didn't really think you'd come, but now - having expended the least amount of effort to do so, she gets to tell herself, "Hey, I tried, I made the effort, and he rejected me. She now gets to feel extra entitled to the feelings she is likely already experiencing (sadness, loss, rejection, abandonment), and avoids facing the uncomfortable truth which is that she caused this. First by having the affair (sure), but secondly, by being unwilling/unable to make the bare minimum efforts in R that you needed her to make (when you when you made it pretty clear that you were prepared to stick around and try your hardest if she did so).
She obviously knows you much better than I do, but even I could tell you that what is likely your last anniversary as a married couple would feel heavy, even without this. As such, this feels kind of 'guilt-trippy'. Whether you went or stayed home (I assume she knew you would stay home), it took away your ability to lick your own wounds and wallow in your own grief and self-pity.
So yeah, I don't necessarily attach sinister motives to her, and maybe it was an (extraordinary limp) "hail mary" for her. But regardless of her intention, I still see elements of passiveness, assurance seeking, withholding of affection, guilt tripping, and responsibility avoidance - and all of those are problematic and features of (unintentional) emotional manipulation.
A small fissure has formed between HikingOut and emergent. I can only hope this grows to its full potential!
How's that? An anniversary gift maybe? Probably not you were hoping for, but maybe that's fitting given the circumstances?
How are you doing today?