These fish have been in that tank since March and the stripey beta was stripey when we got her
she probably was, my 4 were but now there all fully coloured, one took a little longer because she didn't enjoy the busy tank i kept her in so i seperated her and she didn't like that either so i got some new decore and added her back to the other tank and she loves it, it could be because you only have two the other might be bullying her or even the male might be, i have had mine with guppies since february but they turned on one which i then removed, thats the thing with bettas they can change in an instant, i personally would remove the male and if you have enough space get another 2 female, but if you think they are fine as they are then fine
you'll have to come show them off in the betta section