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You can increase self-control by spending time with Jane (The red-haired witch, available at midnight in the Merchant's District Gate), without peeking at her first, so choose spend time right away.

But the lust check is still not that important at this point, if you passed the lust check, you'll only be given the option whether to engage in sexual acts or not. They'll be more important in the future updates, and by that time there will be more option to increase self-control and affection.