It’s clear that your male was performing pouch displays in order to interest your female in courtship and breeding, and that she has responded to his overtures positively, which may ultimately lead to a successful mating between these two ponies.
If you contact me off list at the following e-mail address, I will send you a lot of additional information about courtship and breeding in seahorses so that you will have a better understanding about exactly what is going on between your ponies:
In other words, Charlotte, it sounds like your ponies are showing a healthy interest in courtship and breeding at the moment. I can only speculate as to why your female was so inactive previously, but as lie-in-wait ambush predators, seahorses are naturally rather sedentary animals that do not move around a great deal since they rely on their camouflage for protection against predators, and prefer to blend into their backgrounds in order to escape notice when they are not actively feeding or breeding…
Best wishes with all your fishes, Charlotte!
Pete Giwojna, Ocean Rider Tech Support