if your site is very good, gambling goes on forever and dating stops fast (people get addicted and keep coming back, or people find the person they're looking for and never return)
Gambling is truly addictive and it involves putting in funds by the gamblers normally as there is no free gambling unless you just want to introduce faucets. However, there are so many free to use dating websites today that having a dating website with bitcoin payment will not really move pretty fast unless there are just some who have enough to throw around for something they can easily get free even outside any of the sites.