I have to wonder if their lack of acknowledgement comes from you telling them you are proposing "alone on the beach". One could take that as this is a private for us and we don't want intrusion or any celebration. As someone who doesn't understand the need to share all of their personal life with strangers, if I told them that and then every last staff knew about it and said something I would probably be on the other side of annoyed.
I appreciate this, however I was exploring various proposal options with the Pulo team prior to my arrival so it was clear we weren't set on being alone, nor did I imply we wanted to be alone. I also specified we'd like to celebrate after the proposal, which we did on the Kawayan Bar later that day which we organised ourselves whilst at the resort (and this was the experience later wiped from our bill). We'd also reserved a specific table we liked for dinner.
We openly shared our news with every member of staff who asked about our day or how our trip was so far, even after the day of our engagement. There was plenty of opportunity for this to be picked up or passed on.
One thing worth mentioning is that when talking with staff (including the Watersports Manager - just about the only 'senior' management we were able to speak with) about our engagement, we said how excited we were to celebrate on the Kawayan Bar later that day. Yet again, a great opportunity for Aman to make us feel special, but nothing was done. There were no special touches on the Kawayan Bar and again we felt this was a missed opportunity.
That evening a receptionist at the Clubhouse approached us and asked if we wanted to confirm our sunset cruise for the next day. We said we hadn't booked one. We then thought perhaps this was meant to be a gesture from Amanpulo so we spoke with the watersports team to clarify the booking and turns out it was not booked under our room. Not only did they miss a trick and get our hopes up but they also failed in Aman-level service of knowing which rooms have booked which experience.