Debbi58 with your most recent post I think traveling more often with your partner is just the right medicine for your ails. About your grandkids being sad that you’ll be away, to remember that children get upset about so many things, that doesn’t mean that those things are bad or awful. For them, and for you, “this too shall pass”. Though they may be upset or sad, they will benefit from your temporary absence in ways they can’t understand, as it will hopefully force your daughter to step up to the plate for them. Also their being upset is expected and unavoidable. It is not unreasonable for you to take a vacation.
I won’t comment on your daughter refusing to drive and this being her first job, let alone a part-time one, and her perking up only for her boyfriend, etc as I’m sure you can imagine what I think about that. 
You being unavailable to your daughter at this time (doesn’t have to be forever, just temporary) may be exactly what is needed. However, when you begin to doubt yourself: remember that this isn’t the end of the world, your daughter is not the first person to have been a single working parent with a lull in hands-on support, and she won’t be the last. So please do not feel guilty, you’ve already done enough of that! And when you are gone on your travels, it will likely be difficult for her at first, but that doesn’t mean you must rush back home and cancel your cruise, it means she must persevere. So, might I suggest letting your daughter know that you won’t be available much at all during your trip? And then stick to that, have it be a trip with minimal communication with anyone via phone or text. I only say that because I just don’t want you to be preoccupied the entire time and glued to your phone trying to help your daughter from afar. Like another person said, you deserve this trip (and many more!)
I so hope that you and your partner have a lovely time celebrating his retirement. Enjoy your cruise and when you get back, set another date for another trip! I wish you both (and your daughter) well! 