He was such an attractive young fellow.

那时候多么有魅力的年轻男子啊。

I take this to mean that he was a sexy, sexy man.

我理解这指的极具魅力的男子。

In her case, what I gather from this situation is this is kind of a charming guy enjoying himself, enjoying creating chemistry, maybe doing it with multiple people, enjoying that freedom.

在她的情况中， 我从这情形中了解到的， 这颇具魅力的男子， 享受自我，喜欢营造情感联系， 或许同时与多人如此，享受着那份自由。