Well, for me the part about imagining other partners in bed worked well... Using a dildo as the second guy..
Also asked her to tell me about experiences with her exes in bed, what she did and how she did it... To help you figure out if you have the guts to see her with another guy... Start talking to other guys, show pics of her and if possible with her next to you, see her reaction, let her chat with the guys, then ask her to read it lol
Anyway, everything goes, even exhibitionism like her wearing more provocative, smaller clothes around males. But remember every story is different for everyone, good luck