Frustrated

So I'm not comfortable talking to family about this but the past four it so times of sex my husband just can't keep it hard. He first said because aex was a chore so we started adding new things in but now he says it's because his dad who we don't get along with is living in the apartment down stairs. Today the big 31% chance he couldn't do it! You name it and I couldn't keep him turned on! I'm so sad and frustrated. Please give me some advice!