Is it normal that i still feel this way about him after 4 months?! v.long, soz

When I went to study abroad earlier this year, I made a few friends.

But there was one guy in particular who stood out to me: I could write a whole book praising him, but I know that it'd be really boring for others to read! XP
Besides which, that's not the point of this story.

We were members of the judo club while out there and I hung out with him almost every day as the club practised that often, but we hung out together on other occasions too.
I suppose he effectively filled a boyfriend-shaped hole in my life at the time [although I had one... go figure] and I actually found myself falling for him. HARD.

* * *

One night, he asked several other students if they wanted to come out. In the end it was just me, him and another two.
All four of us went out to a few bars and got drunk and hung out in a convenience store, generally behaving like crazy drunk students
In the end, myself and this previously mentioned guy had sex.
Several other things - which I reckon were actually catalysts for that - happened.
The morning after, he REALLY regretted it and - at the time - I did too.
However, since then, I've found myself replaying the night we had together in my head most days and thoughts of him consume my mind.

He left to go back to his home country at the end of July and I went back in August.

* * *

The reason I'm asking this question, though, is that I had a dream last night where we were actually a couple.
He came in to defend me when everyone else was laughing at a speech I made for a class. I remember the way he held me, and how he held my hand at other moments in the dream.
When I woke up, I felt unsettled and I found myself thinking "Right, I've got to at least TRY to do something about this!"

I don't even know if I am actually asking for help, or just trying to vent.... but thanks if you take the time to read this and/or be sensible about things.