Slumlord advice?

My boyfriend has lived in this house for 2 years, I’ve been here with him a year, and the house, and garage(which we pay extra for) are still full of his stuff! I’m almost 6 months pregnant and we really need his stuff out. He’s aware and we’ve asked him several times to please get his stuff out. We can’t even start to set up the nursery until he gets his stuff out of the spare room. I’m so frustrated! When is enough, enough? I just want to throw all his stuff out!!