It is fairly common among the Summoned, Istredd's fairly certain that monogamy is the rarer of the two. For him, it's always been an open door. He fell in love with someone here when he was already in love with Yennefer. It wasn't something he intended or planned for, it just happened. But he was sharing her long before that with others, so it all worked out between them. It's not something that comes up between them as a problem.

It's why he looks somewhat confused. "You are a good man, you are worthy. I don't know what I'm saying that would make you feel otherwise." His wings flutter a little as an outside visual of his inner turmoil. The last thing he expected or wanted in this situation was to hurt his dear friend.

"Oh." It comes to him then, reframed. Gale wanted to be picked. He's sad and honestly, upset, because he didn't expect this to happen. And now he is in a position where someone he cares for is in pain because he didn't talk about his situation sooner. "Gale, I am so sorry. You must understand, I am not accustomed to other people's admiration, otherwise I would have told you my relationship status sooner."

It didn't occur to him that he was getting attention that was becoming genuinely romantic. Istredd feels terrible about it. He reaches out to touch his friend, to give him some kind of reassurance, but he stops himself. It's not appropriate in this situation. "But Lucifer and I, we're forever. I'll be with him until the day I die."