I believe everyone has their own "must have list of traits" that when compiled together is identified as being a "soul-mate" regardless of their sexual orientation.
Note I said (a soul-mate) and not their "sole-mate".
In a world with over 7 Billion plus people it would be unrealistic to believe that there is "only one" person on this planet who would be our ideal mate.
Odds are there are millions of people who would be perfect for any of us. Being "in love" has nothing do with one's sexual orientation.
Only you can determine if you've met "the one" by confirming (your) list.. You have to (know what you're looking for) in order to be able to recognize when you have it.