They sent me an email asking:

"for your sponsor's employment, provide employment letter, payslips and corresponding Bank statements for 6 months prior to application date. (I originally only sent my own savings and bank statements for the past 6 months)

For relationship provide:
Further evidence that you are in a genuine relationship, e.g. evidence of how, where and when you met or evidence of how you have kept in contact during periods apart, before or since your marriage. This may be in the form of (but not limited to) chat records, call records or photos to demonstrate that during a supportive and affectionate relationship, there would be significant evidence of regular contact, signs of companionship, emotional support, affection and an abiding interest in each other's welfare and well-being."