Multiple Romances

So what you're saying is that if i want to romance Peebee i should not romance Reyes right? Ultimately what i want is Peebee (i actually like her, i see a lot of ppl dont) so i can pass on Reyes.

Well, I know for sure, that sisRyder has got a 'one night stand' option, which is NOT behind the romance-lock.

It happens pretty early in game (if compared to the rest of the BW romance\relations progressions), and it may (or may not) progress into 'something more than that' later. 

You can pick all the flirt options with Reyes, leading up to a rooftop make-out session, without repercussions on other romances--until a certain incident takes place in a cave where you have to decide whether to lock-in with him or break it off.  Alternatively, if you lock in the romance with a crew mate after Reyes' rooftop scene, the rest of his plot line will proceed without flirt options (ending it without having "the talk" so to speak).

Hope that helps. 

Yes you can fully romance as many characters as you want, but as you embark on the final mission, the game will lock you into one romance. To give you an example, I romanced PeeBee, Cora, and Keri on my Insanity playthrough. I got PeeBee's sex scene (the one after her Loyalty mission) first, then Cora's sex scene, and then later on got Keri's romance scene in the bar. When I embarked for Meridian, it was PeeBee I met on the bridge for the final romance scene. I don't know why, I can only speculate because I got PeeBee's sex scene first, but you can basically bang as many romance options as you want in a single playthrough, but the game will eventually choose who's your actual love at the end of the game.

I also base this all on my personal experience. It might be possible I broke the system somehow and got both romance scenes with Cora and PeeBee. I dunno. I never even had either of them confront me on the fact I was with both of them. So who knows.

I know of of one who you can bang with no strings attached.