Hi when having sex my girlfriends vagina is very tight and painful at the start. this happens every time we try to have sex and i was wondering if there is anything to solve this problem?

Vaginismus: This sounds like vaginsmus, i.e. vaginal spasm with penetration. With time, it may improve on its own. Be caring, patient, and slow; it may improve a lot. However, vaginismus can be a major impediment to sexual satisfaction and overall sexual health. If it continues, she should get professional advice. Start with her gynecologist; depending on her advice, perhaps a sexual health professional.