What do you mean when I propose a toast to my girlfriend and she makes another woman drink it?

Girlfriend can't drink, and she doesn't want to blow your mind; Such as driving, alcohol allergy, and having a month;

If a girlfriend can drink, she can't drink enough.

If your toast is an apology to her and someone else drinks it for her, she won't accept it or is not sincere enough;

If you propose a toast to show your love for her, she didn't refuse it before, but this time she asked someone to drink it for her, which means that your feelings are out of order, your feelings are alienated, or she is still angry.

She brought her girlfriend to dinner at your invitation, which shows that your feelings are still very shallow. She came here out of courtesy. When you propose a toast, she doesn't want to accept your affection, or just wants to keep the relationship between you as it is. At least at present, she has no further plans and doesn't want to embarrass you. It's a euphemism for you to ask her to drink instead.