Is it ok to like one of my friend's ex boyfriend?(online)?

I met them 2 years ago, they broke up also 2 years ago, and last year I hang out with him and I feel I fallen in love, that girl found a new boyfriend last year, she disappeared for that period of time, her new boyfriend and her already broke up this year, so she is back and she decided to talk to her ex, my crush again and I feel jealous but she is her ex they still friends, and I'm her friend even tho we don't talk much, but I like him...
Is it ok to like one of my friend's ex boyfriend?(online)?
Post Opinion