Building Sexual Tension gives you that feeling of needing closure. The more of it you build, the more you'll want to fuck each others brains out. And, the greater the mutual desire for sex, the greater the likelihood of sex actually happening. It'll also make sex a lot more enjoyable for both of you.

Tension is something that's created when two opposing forces are combined somehow. To apply tension to sexual attraction, you must combine a force that's moving the sexual vibe forward and a force that actually holds the sexual vibe back.