What is the best SEO technique for a online store?

[Jake]

A dating site is not an online store, it requires a different strategy , you could try adding dating advice articles in perhaps a blog section to try to get on search engines radar, but realistically you will probably have to resort to paid ads to get any usable volume of traffic. Bigger dating sites also have affiliate programs where you pay a commission for new clients, you can be scammed by fake accounts.
Plenty of fish pof.com has paid ads a bit like Facebook, specialty niche dating sites have some success advertising on generic dating sites.
Being active on social media sites, with a business Facebook page, etc. may be a better way to get free traffic than search engines for this competitive field.