So what is tantra about? It is about not intimacy with a person but about the identity or resonance between you and the whole universe and about subtle ways of "seducing the powers of nature" as one modern Indian tantric text has as its subtitle. The intimacy in tantra is intimacy with the whole. Some of the practices of tantra; the more popular ones, can help with intimacy with a partner or help to heal personal issues; but these are a side-effect and can be a diversion. If you strengthen the small ego, the self then you can create more barriers. You are strengthening the spiritual ego; what Chogyam Trungpa called spiritual materialism. This is certainly true if you think that the essence of tantra is challenging restrictions and behaving outrageously. If you can dance naked on the table; you may be drunk or crazy, but you are not necessarily tantric! This was a way in tantra of challenging the Vedantic orthodoxy several hundred years ago but nowadays anything goes anyway. If you realise your essence as the divine you may be enlightened but you may also be caught in a grandiose and narcissistic delusion; "I am a Goddess so everything I say is right!"
Cynically, you could say modern tantra is sexual because sex sells anything including enlightenment; however sex and desire can provide a motivation for practice and can help the skillful development of relationship. Ecstatic states give a taste of enlightenment. There are many traps in all this. For example; there is absolutely no connection that I can see between tantra and polyamory or polyfuckery. Both of which are OK lifestyle choices but very little to do with tantra and again easily subject to much delusion. Relationships just becoming another acquisitive commodity, If there is any sexual lifestyle implied by tantra itself it is probably celibacy and there is only one tantra book I have ever come across that uses the word celibacy with any prominence (it is the excellent Eros, Consciousness and Kundalini by a therapist Stuart Sovatsky for the record).
The real difficulty in teaching tantra is very easy to state. It is much easier to teach about energy than it is about consciousness. Energy is sexy (literally!). It's usually fun and fits with our need for more and more intense experiences. Breath, sound and movement the three keys in tantra are all about increasing energy flow. Consciousnesses by contrast is boring!!! It is still, steady, spacious but empty. However, traditional tantra is clear in Abhinavagupta's first Shiva Sutra; Chaitanyamatma. ‘Everything is Chiti, everything is Consciousness’. How to teach about consciousness and awareness the platform on which Shakti creates the whole universe? How to get people to value the floor and pole which allow the pole dancer to perform? To do this requires loosening our addiction to phenomena and experiences. There are many more methods than the traditional one of sitting on your meditation cushion observing the mind or the breath; though they are still excellent. Osho has given us some methods that combine movement with observation and stillness. Ramana Maharshi has given us Self Enquiry; continually looking for the questioner not for the answer to the question. Of course Ramana was not very sexy - he never got away from his mother; she came after him; and Osho is more cuddly than sexy.