Congratulations SueZee! We're delighted in your marriage, and you've picked a great country in which to honeymoon. May is not too early to go to Italy, although pack a light jacket just in case. The crowds won't be there yet and you'll save some money when compared to the peak summer season.
Where to go is very much a matter of taste. Most definitely you need to go to Venice and I'd say spend at least 5 days here, maybe with a day trip or two (such as to the glass making island of Murano or to Padua or Verona). You mention Bologna, so that's on your list for a few days. Lake Como is a little cool in may be very romantic, but it's out of the way from most of the other places and you'll spend hours on the train going to and from it. But if it moves you to be there, include it.
Rome might be a little busy for a quiet honeymoon, but I'd really recommend you visit Florence. The wonderful history of Florence and it's great art are fabulous.
So how about something like this.
1) Fly to Venice. 5 nights here.
2) Train to Padua. 2 nights here, with optional day trip to Verona (or make Verona another destination for a night or two)
3) Train to Bologna, for as long as your husband wants to eat here
4) End trip in Florence.
5) Last day, take train from Florence either back to Venice for flight back, or to Rome's Da Vinci airport.
Enjoy the trip! I know some of the others on these boards will advise you, too.