|>>|| No. 13449
If you give her the job, you could be accused of favouritism. If you don't give her the job, you could be accused of spite. If she gets the job and an issue crops up down the road, whatever contact you had with her on the dating app could be used as evidence of your amorous/malicious intent.
Just tell your boss. As soon as you tell your boss, it's his problem, not yours. It might be mildly embarrassing, but it'll be far more embarrassing if it comes out later and it looks like you were hiding something.