Could it be possible that you, at some deep level that you don't want to acknowledge, are still in love with him?
If that's the case, then the High Priestess could represent that part of you that you've tried to deny. It could represent some sort of feelings you've been hiding from yourself, and its position in the future could mean that those feelings will soon be brought to the light.
The Ace of Cups could mean a rekindling of the romance, or perhaps wishful thinking. What were the cards in the position of the Crowning card and the foundation? (I've seen different layouts list the order differently, but I'm talking about the cards directly above and below the first card).
The Ace of Cups could also mean that you need to look at whether or not you're truly satisfied with your situation. Do you want him back? Would it bother you to see him in love with someone else?
Hope that helps!