I've had multiple groups of sveni and ime they're some of the hardest to tell apart until they actually pair up and spawn-- and I've bred a lot of fish for a long time, including other geos. No real color difference, fin differences can be as much about the individual fish as gender, and judging by size, a good indication with some geo species as they get a year or so old, can be ambiguous since, again, it can be the individual fish as much as gender. For example, my current dominant breeding pair were the two largest of the group and the female's fins were actually longer. It was only after I separated them from the group and something like six months or so of spawning activity that the male began to gradually outgrow the female to have at least a 1.5 inch size advantage now at over 3.5 years-- she's still one of the largest in the group. Among the others I'm not certain what I have, one smallish, the others larger, two have teased pairing up and spawning with no results and half the time they ignore each other.
All that said, it does sound like a male courting a female, but not seeing them in person it would be hard to guarantee. If they pick out a rock (or something else) to start cleaning, along with some head shaking, etc., you might be in business.
