Can friction from sex cause blisters on a vagina. They don't hurt and they aren't red they just itch really bad. Me or my fiancé have ever had herpes?

Blistering. Sexual intercourse most commonly causes redness or slight excoriations which may be uncomfortable. A topical lubricant sometimes will help alleviate this. Blistering is not typical and is most commonly associated herpetic infections even if your only symptom is an itch.