why is he flirty texting her and never you, maybe he doesn't see you that way at all, and only as a friend. it is hard to get out of the friend zone if you have been in it for awhile or the other person cannot see you as anything more. you could jokingly ask him why don't you ever send me flirty texts and laugh, and see how it answers. if he goes that would be weird or something like that you know he doesn't like you that way.
When I tell the truth, it is not for the sake of convincing those who do not know it, but for the sake of defending those that do.
William Blake