Sounds like you'd have some funny stories. Never had that happen to me, and honestly can't say I'd want it.
ANNNYway, most of my Shepards typically end up with one person. My canon only romanced Tali, secondary only romanced Kaidan, third romanced Liara and switched to Garrus, fourth knocked boots with every human female in the MEU, and fifth is staying loyal to Ashley. Thought I'd try a Jacob romance with one (which I probably won't import to ME3) and another would romance nobody.
I haven't had a Shepard who romanced anyone but Miranda since ME2 came out. I only romanced Liara once, and it was a ninja-mance when I trying to get her character's achievement for the 360 which meant I had to use her a lot.
I still have yet to play a Femshep through ME2 and ME3. It's looking less likely that it would ever happen, since I basically hate all the Female LI's. Only Thane's is tolerable, and even then, he's an alien, and it's more of a mature relationship that would be doomed to fail. Garrus' would be alright if he wasn't awkward and socially inept (and an alien.)
As I've said, I wish there was a human LI for FemShep that was a suave, smooth playboy and charming rogue kind of guy who knows how to push women's buttons leaving FemShep irritated, while also being utterly intrigued since she's the only woman who could resist his charms. Bit of 007 mixed with Han Solo, Lando Calrissian, Indiana Jones, Captain Jack (Harkness and Sparrow), Face from the A-Team, and Wesley from the Princess Bride.
It doesn't help that I personally think the two best romances FemShep has are 1) MaleShep, and 2) Miranda.
I'm not a fan of the whole 'awkward thing' that people sometimes are drawn too (especially with the romances). I'm very much the alpha male type person (and as you all know, I do have a tremendous ego), and I can be the insufferable jerk ass when looking at it objectively.