AP and Anger

In my experience, they know very well. Helpless anger, or frustration, is especially rampant during the break up phase of a relationship and may very well lead to physical violence from an AP, and at least lead to protest behaviours (which you could call attempts at manipulation).

I wonder because I haven't seen much anger expressed by APs on this board. Much more longing and yearning. So I wondered if they are aware of the anger? But perhaps the posts about what "DAs do/have done to them" is the anger.

Can the anger be subsided with more reassurance from their partner?

Yes, there is a lot of repressed anger from APs, towards both parents and partners from not having needs met.
Anger often turns inwards, but sometimes through protest behaviours like manipulating the partner in order to get their needs met.

I also believe that the intense longing that APs experience is conflated with love, like tgat suggested.
It's rather a need to be validated. Perhaps there is some true love in it (I'm trying not to be black and white), but they are often mixed up.

I believe that anger can be reduced with more reassurance, something which will deactivate attachment strategies.

I remember one episode, of which I am not especially proud of, with my ex. I was struggling to put on a heavy backpack before we started on a hike. She noticed it, and tried to help me. I lashed out at her instead of welcoming her help. My "failure" core belief was triggered at that point. I felt like a failure for not managing to put a backpack on. I was probably irritated about something else, but still. Just an example of how self-hate can sometimes be turned both inwards and outwards.

Oh man, I know this all too well.  I offered to help my ex before going on a trip.  He said, You're kidding, right?  I don't need any help from you!  He seemed angry, but I shrugged it off.  Geez, I was blind.

this really highlights the incongruence of AP's demanding signs of love and rejecting them when they happen! it's an endless loop. such a toxic dilemma.

I like this topic. I have never really been able to get in touch w my angry side when the relationship ends. It's something I have talked w my therapist about too. I am usually too sad and I fully believe it is better to understand where both sides are coming from rather than be angry. I feel like that is a cover up for other emotions and logically I know it is ridiculous to be mad at someone for having different feelings than myself.
I don't like feeling angry at this person I claim to have feelings for. I feel somehow like being mad at them or saying mean things about them is really just being mad at myself and saying mean things about myself.