Hi Ahm.

It sounds like your dreams are a sort of 'wish fulfillment'. You know he's in a serious relationship, and you are not. You are subconsciously wanting the same thing.
You were together for 3 years....it's hard not to feel
something for someone you were with for that long. I agree that he's not the one you want to be with. He's just a 'representation'.
A party and being 'sucked into' a drain, together with 'being with' your ex, is your subconscious telling you that you don't want to be 'pulled into' just any relationship, or one like you had with your ex. That you want more than just parties, and fun. You want a serious relationship.
Just take a few steps back, and don't worry about whether or not you have what he has. Take this time to discover who you are, and what you want out of life.
I know it's cliché, but seriously,... There is someone for everyone, out there.
Hope this helps you out.