3 years single?
In that time I would have filled 3 little black books.
Your only seeing them if you sleeping with them, Your only an official item after you've had "that" conversation. Only after its official should your morals come into it.
Date all 3 of them. Not for long though or it'll get awkward and complicated. Then choose.
If your really good you can convince all of them they're better off just being friends with benefits for now. Keep that up for 3 months, it never lasts longer then that anyway. Then choose. Win Win tbh
Only listen to me if not serious about any of them.