How to avoid a romance with Liara???

I have a female Shepard character and I've noticed that she is close with both Kaidan and Liara. But, even though I like lesbians, I wouldn't like Shepard to end up in a romance with Liara. Liara was talking that she was interested in Shepard once and that she felt a connection or whatever, and I had Shepard turn her down openly saying that she isn't interested in her. Then I went to talk with Kaidan and they had like a "flirty" conversation. After a few assignments I went to the lower deck where Kaidan and Liara are and I went to Liara first and even though I was choosing the repetitive answers the conversation ended with Liara talking with Shepard like I didn't turn her down earlier. Then I went to Kaidan and he didn't have anything to talk except his thought on the last mission... Please help me. I already did a spare save so if something goes the way I don't want it to, I can load that one so I can correct my mistakes but I wouldn't want to go through the trouble of finishing assignments and missions all over again if something goes the way I don't want it to. I've read other articles on this topic but I didn't understand a thing so keep it simple. If there is a way tell me how to do it and that's it. If there is not than I suppose I start a new game and finish the mission on Feros, Virmire and the other planet before I meet Liara because supposedly if you do this the relationsheep between Liara and Shepard will remain on friends... I'm a guy btw... Please help...