It is only inresponsible gamblers that would going to hide there gambling habit from there partners. Normally as a good gambler that normally gamble fun and entertainment with only what you can afford to lose, I don't see any reason hiding it from your partner. Because it is not when you would be having challenges that you would start letting your know that you are a gambler, by then she might be seeing you as someone that is not genu. However, as long as you are gambling responsibly telling your partner about it might be the best way have more trust.