Have you heard of Carmilla? In its first life it was a vampire novel that predated Bram Stoker's Dracula by 26 years, but even in that incarnation, Carmilla was quite clearly a lesbian. It's almost comical how the heroine, Laura, fails to notice what her strange new friend is up to. Carmilla is constantly stroking Laura and declaring her quite literally undying love for the girl. She even says she wants Laura to die and be resurrected so they can be together forever. But as smart as Laura is - and she is very smart - she's lived such a sheltered life that she thinks Carmilla is just a little flaky. It's funny and scary all at once, since Laura has no clue that her "friend" is a supernatural stalker who's killing her a sip at a time.
In 1970 Hammer Films turned Carmilla into a movie called The Vampire Lovers, and they actually made the lesbianism of the story even more explicit. Then they cast two incredibly hot leads (the dewy innocent Pippa Steel as Laura and the irresistibly sultry Ingrid Pitt as Carmilla) and gave them a love scene that, even though it's softcore, must have shocked the hell out of 1970 audiences who thought they were in for a mere horror movie. But I can't imagine they were unhappy for very long. The sight of Pippa's perfect breasts would cure any ailment. Let me share that love scene with you - and then the seduction/betrayal scene that comes right afterwards.
Carmilla works her mind control on Laura first, with nothing more than a kiss, and before long Laura is naked and rolling wide, glazed eyes as the vampire teases her nipples and then bites her just above the areola. No necks for this lesbian vamp! She's after sweeter prizes. And yes, the breast bite is in the original story too. Read it, if you're interested. You can find it free here.
Then in comes the governess, who until now has been a kindly, protective figure; but before long she's fallen even deeper than Laura under Carmilla's control. Watch her face as she slides from groggy compliance to surprised arousal and finally outright lust when Carmilla lures her into another room and undresses. You won't have any doubts about what happens next, even though it's not shown. You just see the governess looking very satisfied the next morning, and after that she's become a perfect Renfield.
Unfortunately, there's no way to embed a video on Blogger in such a way that it starts at the point you want, so I'll have to give you the whole movie here and tell you to skip forward to 44:58. That's where the Laura/Carmilla scene starts, and the governess scene comes just afterward. Oh, and here's a tip to help you enjoy the scenes even more: pay close attention to the details of Laura's dream. It's chock full of lesbian innuendo.