Is it okay for men to preach if they don't love their wives?

How a person is treated, even if it's by a family member, isn't a litmus test for the pastorate. I think that allowing it to be a litmust test is a perversion of the verse calling for a pasor to manage his household well. Note that it doesn't say "perfectly". Further, I submit that it says more about people who are willing to gossip about the private life of the pastor and his wife, than it does about the pastor.