DEAR ABBY: My husband, “John,” recently returned from his fourth Middle East tour after having been gone for a year. As soon as he got back, his mother invited him and his two sisters on a vacation cruise for a week. He said yes, and they’ll be leaving in a couple of weeks. The downside is — no spouses allowed. John and I are in our mid-40s. We have been married 25 years. I feel slighted, left out and, frankly, disrespected. I’m not sure how to bring this up to him or to his mom. I don’t want to cause ...