Mass Effect Legendary Edition review. (Contains massive spoilers.)

With Steve, there's no way for a male Shepard to tell him outright if Shepard is only into women, so if you help him out enough that you get the invitation for drinks, he will always comment about there being an "energy" in the bar and about "graceful dancing."  Shepard can then use the line that he likes watching the dancing on the stage.... at which point Steve will always interpret that as Shepard being straight and the conversation will become focused on being just a good friend.

The only other awkward line with Steve is in the conversation where you're telling him to take a break.  You can avoid it by not using the blue paragon choice and selecting the "that's an order" line instead.  I believe you can even select the option where you leave the choice up to him and you'll still be able to find him in Normandy's docks and progress with helping him.  I think that some players are "afraid" to use these lines because they fear that they're "not nice"; but sometimes being "nice' means just avoiding sending out a wrong signal, too.

The romances in ME3 are easily managed since all of the invites that lock them in stay "open" until just after Thessia (and by then you will have collected them all).  All you have to do then is talk to your chosen LI first and the rest will be locked out at that point.