The earlier advice was one-sided, yes. There should be a company policy on harassment / relationships, and it's not always as restrictive as people here assume.
There's a universal rule against affairs with a subordinate, and for good reasons. Harassment / unwanted advances - usually explicitly prohibited. Otherwise, consensual relationships are not always a concern for HR. In a larger company / different departments, the downsides are not that significant.
Don't do that over company email though. It is stored somewhere. There is likely a separate policy on email use that can be used against you.