A lot depends on what house we use to identify him. The usual house would be the 7th ruled by Mercury; but someone who is now more of a friend/co-worker would be an 11th house matter. A casual love affair would be the 5th.
In horary, it matters a lot whether planets are applying or separating. A separating aspect doesn't confirm a sexual relationship. Regardless of whether the motion is retrograde or direct, the perfection of an aspect is the "yes" testimony.
You are signified by Jupiter, but it is retrograde, and turning away from the other significators, perhaps indicating second thoughts. Mercury (7th) and Venus (11th and 6th) do not aspect Jupiter, and Mars has passed its aspect with Jupiter. Mars is in Jupiter's terms, but all-in-all, I don't see a "yes" that is resoundingly powerful. The moon (your emotional stake in the matter) does make a nice sextile to Venus, but as the more dignified, faster-moving planet, it would be up to you to initiate something.
I'm not trying to moralize here, and I don't know the nature of your workplace. But if you two work together for the same employer in something like an office, you'd want to think through how sleeping with a co-worker would play out with your fellow employees, as these things are hard to keep secret.