A married instructer?

I recently found out my neice has been dating a married man. Its supposily he has marriage issues n wants to be divorced but has no where to go. He seems very nice. Has given her gifts n never on one date has she spent a penny. Its just thats adultry n Idk if she should perticipate in an affair. She does appear to have feelings for him. What was first a month dropper was the began to date a week after a class was her's was over n he was her instructer. From what I know a few ppl know at the college but in general it is secretive there. What is ur opinion of this? She seems to be happy he appears to be quite nice, but is legally married n just taught her in his first class. Its been awhile now and I believe she said she loves him. I need ur opinion...