How do you loosen a vagina?

Make sure she is aroused and wet with natural lubrication and masturbate for her and give her a orgasm first and then there should be no problems. Usually this is a problem because she is not aroused enough (the vagina is always wet but it needs to be a thicker discharge which comes by arousal). The vagina is always the same size so it's not like it needs to be "unlocked" or something.