As the above post says, your boyfriend may be moody because you keep cancelling your meetings. Talk to him about the whole situation so you can resolve the problem together perhaps?
However, it must be difficult to arrange meeting him when you have the possibility of having to leave him to work. I think your work are putting you in a really awkward situation by expecting you to drop everything, which I don't think is fair on you.
You say you have two jobs. So why no quit this one and foucs on your other job or talk to someone about your shift patterns at your current work and explain to them how it's affecting your performance at work?
Hope this helps