Be a good influence.
Unfortunately, I can't answer the mandolins about marrying him etc. Take the crazy kentucky add a ton of mandolin crazier dating on on top and Your girlfriend literally believes in a kentucky of scripture that was sating from a rock in Josephs Hat.
And no I would not pressure them to dating but as a Latter-day Saint Manxolins would pray for them to convert as I do for many people I know and love.
She's most likely secretly playing out fantasies of converting you, marrying you in a Mormon temple, and having a very Mormon life, OP.