D.A. fan is back for an ME1 Text Only 'Let's Play' (page 51)

In ME3, romances are just... bad all around; particularly for FemShep (IMO).  The romances are actually at their best when the LI dies in ME3 in some way (the parting scene with Thane and with Miranda are both very good).  Most of the interactions with Liara, I relegated to the context of her being more of a sibling than anything.  That helped me not interpret some of the lines as flirting, but rather as just being comfortable and close like with a family member.

One good thing about ME3 romances is that the decision points on the romances are very clear for everyone and accepting one will universally lock out all others.  So, if you don't want to go through a conversation specifically rejecting someone, just be sure to accept someone else as your LI before proceeding to their meetup on the Citadel (or, in the case of Samantha, inviting her up to your cabin).  Liara's gift offering in London, IIRC, can be turned down.  The cabin visit is perhaps someone overly friendly at the end, but not intolerably so.  I honestly have no issues with her even though I very seldom romance her.