Create online dating 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.
You'll then have to upgrade to a dedicated server, which will cost you much more.
They will also help you customize it to your liking for a fee.
Platforms like Wix or Word Press are also an option.
Just keep in mind that if you plan to go to other niches you'll have to get additional domain names.
It's unlikely millennials in New York will be interested in a dating website called Utah Senior