The second biggest problem with loving your characters too much is that you find it hard to make bad things happen to them. I'm forever telling students - raise the stakes! Make your character suffer. Sometimes we do an exercise where I get them to write down the absolute worst thing that could happen to their main character, other than death. They do as I ask, and come up with assault, bankruptcy, betrayal, severe injuries, etc. Then I tell them that they have to try to make that terrible thing happen to the character in their story.
They are usually horrified. And try to find all kinds of reasons why that wouldn't be possible. In fact, for one or two, the catastrophe wouldn't be possible, but for more than 90% it is not only possible but it would give their story the drama and conflict it often needs. I don't force them to do this, of course, but I want to at least raise the idea and let them think about it.
I have the same problem. Many of us do. Our characters cruise too easily through their lives, and the result is low tension levels and a reader who says "so what?" In a middle grade novel I've been rewriting again, one of the things I've struggled with is the knowledge that I don't love my main character. I like her, I like writing about her, but I don't love her. It's caused me problems in terms of moving her close to the reader, and feeling as if I am inside her head (mostly solved by moving into first person), but as it's a suspense/mystery story, I've had no trouble putting her in danger and injuring her!
One of the things I liked in the Deaver novel I read recently (where the main character is Lincoln Rhyme, the paraplegic investigator) was the way in which the other major character, Sachs, was tricked and nearly died as a result. Rhyme's ability to analyse the information in connected crimes saved her. Right up to the last minute, I thought that this time she would die, and this was because the villain seemed invincible. That's the other side of tension - a truly dangerous foe, not a cartoon baddie.