Ask your partner to see a doctor to be sure there is no issue. Also, perhaps your partner is not as ready or eager as you are, and is not telling you so.
Hi,
Yes, it's still possible to have intercourse w/your partner if the vaginal opening appears closed, although you may need to use more lube during foreplay, and go more slowly during penetration. It's possible that your partner might be unaware that her vaginal muscles are tightening, which can be due to anticipating pain, or not being fully aroused. Make sure she is willing, aroused, and relaxed enough before penetration in order to be successful.
Good Luck