What squad members romance together without Shepard?

I didn't romance any character in the first two games, but romanced Liara in the last part.

Now, I found Garrus and Tali kissing in the main gun calibration room and wondered if there are any other intra-squad member romance scenes? For example, would Garrus be with Liara if I had romanced Tali instead? Would Tali be with Liara if I romanced Garrus as a FemShep?

I'm not interested only in this trio, but curious in general: which teammates romance each other in Mass Effect?

No, this is one of only two visible romances on board, other than your own. The other is Ken and Gabby, as per @ERazER's comment. I personally haven't seen that one. While it may be implied that other relationships may happen, there isn't a scene to walk in on for them. In any case, they don't involve your squad mates, except Joker and EDI. Can't see them making out either.

Ashley and James Vega hook up during the Citadel DLC: