My dh travels 3-4 nights a week, and this is what I do. If he's gone 3 nights (most weeks), I figure that is 6 meals I'm going to eat alone (lunch nad supper; breakfast is always the same stuff)
When he is home, I cook every night (I like it, he likes it, works for us). I make a decent size portion of whatever. Enough for 1-2 portions of leftovers. Then, I eat those leftovers when he's gone. If he travels Tues, Wed, and Thurs nights, I eat the leftovers from Saturday on Tuesday, Sunday on Wednesday, etc. That gives me enough time between meals that it doesn't feel as if I'm always eating the same stuff.
I also eat easy stuff that he doesn't like--egg salad and fried eggplant being my top two. And, I'm always good for Ramen.
And, for one meal a week, I either go to lunch with a friend or get take-out or have a Trader Joe's frozen meal. Something that I really like and that feels like a treat. (This especially, for me, helps curb the jealous bug that he's out staying in hotels and eating on an expense budget while I'm at home trying to be frugal
I'm a consummate planner, so I actually have a weekly meal planner (breakfast, lunch, and supper) that I make every week, writing all this down. When it's meal time, I don't like to think.