I think that the best way to monetize sites with SweetDate theme is points management for users.
Members can be buy points or receive for activity. MyCred plugin is compatibility with BuddyPress and rtMedia.
Members can receive points for send message, send invite, add profile photo, add photo to album etc. (details http://mycred.me)
For example:
1. Members with most points will be display first with search resuls in “Members” site. He will be most popular. Members would like to collect/buy points to be higher in the search results.
2. Members can spend points to gifts (MyCred plugin is compatibility with “Buddypress Gifts latest 2014” plugin.
3. Members can spend (or receive – the issue of setting) points for send message or invite etc.
There are many ways to motivate users!