Its always hard to say, – it could of course be another male, which would explain if the male is a bit hostile … however, it might also just as well be a female.
In my experience it could be that what you have done is putting together two fish which have been under less good conditions, – travel, shop and all that, – any female would not be ready to spawn yet.
The male however is eager and makes bubbles right away, and now he thinks the female should just be right on the spot 🙂 … which of course she is not.
She needs maybe a few more days, some more food or maybe she just need the male chasing her in order to get into a spawning mood.
This could well be the scenario as well. Best thing to do is to really provide good dense hiding space for her / him and see what happens in the next days.