sometimes if the person has had trauma such as they were raped or other sexual abuse it hurts to have sex because the person even though they are interested and wants it to happen they fear having intercourse so they either consciously or unconsciously tighten up whch causes paiful after effects - sore internal muscles bruising and so on. If the person uses douching between periods without recommendation from a doctor they are distroying the helpful normal organisms and ph level that normally kills bacteria that gets in. So the person goes through frequent and painful yeast infections just as fast as one is gone another takes up residence because the ph level needed to fight them is gone. The same with those frequent bathers that clean by allowing the shower to spray right on in so to speak ( this also causes back up into the tubes and contributes to endometriosis),

Sometimes a woman is actually alergic to semen which also causes pain and problems using womens condoms expensive but they protect not only inside but the outside region as well.

If people who engage in masterbation arent cleaning their toys - even if they are the only ones using the toy they can keep reinfecting themselves with yeast spores.

yes when one partner has an infection the other is most likely infected or carrying the spores and not know it.

good luck. hope things finally work out for you.