Ditto what HMA said.
I would sit down with both of them. She doesnt know how to have the talk, they are inexperienced, you aren't. So start the talk with what you see about their relationship (positive), how you would like to see yourself with her/them and see what happens.
Just for helpful hints-maybe print some of the definitions off of lovingmore website? There are some good ones there.
"Love As Thou Wilt"