Own your own dating web site
If your niche is for people 50 and over, an app may be optional, at least in the beginning.But if you're going to cater to anyone younger, a mobile app will probably be more important than your website.If you're going after local singles, consider making fliers and putting them in the places where they are most likely to hang out.
Finally, you might want to consider a freemium model.
They will also help you customize it to your liking for a fee.
Platforms like Wix or Word Press are also an option.
There are even Word Press themes and plugins devoted specifically to dating sites.
For any online business, your domain name will be your most important asset. If you're going after a particular niche, you can incorporate that into your name.
Search for own your own dating web site:
This could be in your own city or region, or it could be a dating site for people with specific needs or interests.