Every single person you exchange sexual energy with leaves an imprint in your womb. Now as we know it the womb is the seat of our subconscious mind, creative storehouse, & potential. If we aren't consciously clearing our womb - we are constantly muddled with others subconscious imprints left in our energetic & emotional bodies.
However, why would God create us man and woman if we were to just dissolve into self inner union? Then we wouldn't actually need each other at all. And true Tantra & Yoga is about union.... yes outer and yes inner. But approaching from such a dogmatic standpoint that we must be fully integrated inner union before we can have outer union is just ridiculous ... It is quite rare that any human on this planet is fully in inner union.
When we can see this all from the higher perspective, and see the kindred souls coming in and out of our life for such reasons of growth & ultimate freedom our soul is yearning for through the intimacy & love we share. We can understand, not go into story, but just ALLOW life to unfold. Growth and self development is best done when LIVING, without a story. Life and existence is always going to bring you exactly what you need for your highest growth potential. So patience and trust in this higher force, is needed.
Like anything, when you are looking for it, it is bound to never show up. Because behind that looking for is a desperation, a need, a feeling of lack; and the universe works in such ways, that it will not give until you are free from those qualities of need and lack. Rather gift you when you least expect.