Zeff is interested to a point but he understand as things are now that would be more of a problem so he doesnt act as it would destroy the group if picked one, he have other priorities but at the same time I suspect he not against it because how he lived his previous life and where that got him.
But for now he is not going to do anything that endangers the group and he is aware some of the girls do like him and the result of what if he paired up with one.