I don't think there's any research to confirm the significant others of black athletes specifically other than looking at each one individually.
You're confusing data gathered for married black people making over a certain amount of money with simply knowing who black athletes significant others are.
As far as I know there is no database or source of data that will let you know who these niggas are dating other than looking with you own eyes at each individual person.
Common sense should tell you that since there isn't a high number of Black folks who make over 100k that any study covering that group would include Black athletes. So you can look at numbers from a study of that group of people and come to some pretty certain conclusions. If over 80% of them do *insert thing here* then you can very safely assume that even singling out 1 specific group of an already small group of people in order to find that they significantly go against that initial study as you're suggesting it would have to be an astronomically high number. Basically you're eye test would have to show higher than 90% of pro athletes marry outside of their race which we all know doesn't happen