Recommendations for solo, relaxing beach trip?

I’ve had a super tough year and am hoping to take solo, a relaxing beach trip at the end of August or early September this year for 4 nights/5 days. I’m not a big partier and would more so like to relax on a beach all day with a book. I’m female, in my late 20s. I don’t think I would do all-inclusive since it doesn’t seem worth it (but could be convinced if people say otherwise) and would just pay for my meals at the hotel restaurant(s). Would welcome any recs on which island (was thinking maybe the ABCs since below the hurricane belt) and specific hotels/resorts. I’m currently limited in walking far distances so not really looking to do a lot of city walking either. Was hoping for direct flights from the U.S. as well. For hotel and food I’m hoping to spend under $3k. Flights under $800. Thank you!