When having penetrative sex is difficult or impossible...

The genital area in both genders, is supported by a group of muscles called the pelvic floor muscles. They are shaped like a swing and they surround and support various organs (bowel, bladder, reproductive organs,...) to prevent them from prolapsing or falling.
The pelvic floor muscles play an important role in helping us with basic function such as passing urine or faeces as well as preventing incontinence, but also having sex.
In sexual function, for male bodies, the pelvic floor muscles help with getting an erection and ejaculating. For female bodies, they help with blood flow and vaginal contractions during sex and orgasm.
Vaginismus happens when there is involuntary spasm of the pelvic floor muscles, in other words when they contract and obstruct the entrance of the vagina, rendering penetration either difficult and painful or even impossible.
Vaginismus can be Primary and this means penetration has always been difficult or impossible from the first attempt at penetration, or Secondary which means that difficulty with penetration started after a period of penetration without pain.
Causes of vaginismus are multiple. They can be:
biological such as irritation of the vagina from an allergic response, vaginal dryness, side effects of childbirth, inflammation of vagina, bladder,... endometriosis,...
psychological such as trauma of sexual nature or not, self worth, confidence issues, fear of pregnancy, phobic response, sexual orientation, fantasies, body image,...
and social such as abusive relationship, partner's technique, not attracted to partner, rules of living from upbringing, social expectations, sex education,...
Treatment will often involve a combination of resource of which a Pelvic Floor Health Physiotherapist and a Psychosexual Therapist. Learning breathing techniques and the use of dilators will be part of the journey towards recovery.