To the OP, once you can show her some money and as long as you aren't neglecting her or your family and other responsibilities it shouldn't really be an issue. Hell, even if you're losing money yet keeping a good balance between poker and the rest of your life it should be fine... so long as you aren't going full degen.
I mean whether it's video games, drinking with friends, or whatever else you like to do with your free time if you are doing it in excess and neglecting other aspects of your life because of it your significant other is going to notice. However, in moderation poker should be no different from your other free time activities. Just explain that you set aside a certain amount of money (and time) for poker each month and that it is your hobby -- you could spend that money/time on video games instead but the difference is that with poker you might actually be able to make more money and take her on a nice vacation with the profits.