[quote=Voltaire]
Is it possible to romance everybody in a single play through of ME2?
[/quote]

Kinda. You can get everybody up until the point where you kind of have to "lock in" your relationship with somebody, but if you're "locked in", you can break it off with them and go to somebody else, but you can't have everyone on the go at once. 

Gonna work on my SB post soon.