I always get told that if you take Depo-Provera for a long time it can be bad. What are the negative affects of long term use. My bf wants me on the pill?

Bones/bleeding. Within a year of use, 85% of women either have no periods or normal ones. The other 15% having chaotic bleeding up to every day. It can take from 3 to 31 months after use to regain fertility. Long term use can mobilize more calcium from your bones and increase your lifetime chance of fractures.
Long-Term DepoProvra. Depo-provera is a safe and effective contraceptive but long-term use (greater than 2 years) can lead to bone mineral loss. Provera (medroxyprogesterone) is a Progesterone only contraceptive but estrogen maintains bone mineral. The complication is higher if other risks for osteoporosis (family history, alcohol/tobacco use). Take extra calcium and vit d. Your bf may have a point. See your doc for details & options.