In my canon playthrough Shep actually breaks up with Liara in the third game, to spare her the pain of what the future might bring - so Shep ends up alone, with no one to comfort her before the final missions, and it is a gut wrenching, lonely sensation, but it was appropriate for my character. In my last playthrough I chose to maintain my romance and that was rather well done, too; Shep feels like she has someone there for her, someone to fight for and someone to come back to ... it's powerful in a different way; especially when I think I might die on the station. This picture captures the aftermath of that very well.