Abidjan,

I am assuming you are bot hflying Y from LHR-ORD.

If this is the case, both you and your girlfriend should be able to use Park Lane - you because of your PLAT status, and her because of ger GOLD status (accoring to AA's website, GOLD members can check-in at AA Business Class check-in counters).

Even if she was not GOLD, I don't think you would have a problem, especially if you are travelling together, nad you are PLAT.

Have a good flight!