If you gamble it is of your interest and that of your spouse, you both need to share same orientation about gambling or given a chance to understand and respect the other person gambling choice and if they won’t then either they go or you reconsider your choice. Why should an adult keep their gambling choice away from their lover that’s deceit to me. Gambling is not a dirty secret.
Gambling is certainly a choice for everyone, and it's not a dirty act. However, in certain circles, some people consider gambling to be very bad, and some people won't tolerate gambling for any reason. If your partner is like that, you certainly know what to do.
There's nothing wrong with adults gambling, what's wrong is perhaps when the gambler is in an environment that isn't appropriate for disclosing their gambling.