To answer your question on kissing, fish don't "kiss".
Kissing gouramis are thought of as a romantic fish because they "kiss" so much, but it's actually a test of strength/ a show of aggression.
Swordtails are probably trying to fight, just have little mouths.
As far as a divider, go to wal-mart or a craft store, and try to find "nylon needlepoint screens" They're white screens made of acrylic. I was going to use them to seperate guppies when I wanted to try to isolate genetics and actually control their breeding.
Works well, even if you have to push it down in the gravel pretty far. (has a tendancy to float, but it's easy to wedge it in the gravel where it will stay put.
I bought some.. how big is your tank? I have some sheets that I had.. most of them got cut up for other projects (wrapping around the intake of a powerfilter to keep shrimp and fry from getting sucked in) but I have about 3 pieces sized perfectly for a 10G. Could send you one for shipping.
Also, if it was me, I would just add a lot of hiding places. (plants, woodwork, rocks, etc) and let her come out when she is ready.
My platies fight, but the picked on one has turned into a ninja. It stays in the shadows all day (in the plants) but seems happy. When the aggressor isn't in the main water column, the ninja will wonder out and explore until the aggressor chases him back.