Volunteer somewhere that needs workers in groups (like the library, they have book sales and need help sorting the books).

Does your boyfriend work? Get him to introduce you to his workmates or go to a work party with him to meet some of the people there?

If you have a hobby of any sort, get to know people at a store that features supplies for the hobby or take lessons (I took quilting lessons at a sewing store, for example, and became friendly with the other women in the shop and who came to work/take lessons in the shop).