u/No_Presentation_1443

I watched this as a kid dubbed in Spanish, so I have limited details, but here's what I remember:

• It's a B-movie, likely from the 80s, possibly European (Italian or Spanish production, but could be English-language)
• A man lives alone guarding ancient ruins hidden inside a large cave or cave system — the ruins looked Mayan or pre-Columbian in style, but were not out in the open; they were completely underground/hidden
• A woman arrives (possibly a researcher or scientist) and there is initial conflict/tension between them, which gradually turns into a romance
• They eventually have sex
• Shortly after (next day or soon after), something attacks — some kind of evil force or entity
• It is revealed that the ruins are actually a portal or mechanism designed to stop/contain this threat
• The man turns out to be not human — some kind of supernatural or ancient being whose purpose is to guard the ruins
• He sacrifices himself to activate the ruins/portal and save the world
• At the end, it is either stated or implied that the woman is pregnant with his child, who will also be a non-human being like him

I don't remember the actors, language, or title. The tone was epic fantasy mixed with dark romance, not comedy. Low budget visuals.

Any help is appreciated!