He asked me to marry him then changed his mind

My boyfriend and I were together for 2 1/2 years. He has a 5 year old son from a previous relationship, and I have a 6 year old son also from a previous relationship. We were so in love, he wrote me love poems, told me I was beautiful every day and treated me like a queen. The only time we fight is when the kids are around,( shared custody, week on week off for both of us) its usually him being over sensitive about his son, and also me being over sensitive about mine) We were engaged for 2 months, and moved into a new house together. We lived there for one month and he had been acting distant for a while when he finally came to me and said he wanted to break up. The reasons he gave were he thinks my son and I are rude to him and his son, he's tired of always being wrong and me always right, and not enough sex. We agreed to work on these issues to try and work it out, but a week after this he tells me he doesn't love me anymore, and he's staying at a friends place until I move out. I asked him why he feels this way he just cant explain it, he just doesn't feel the same anymore he says. I'm devastated. it went from we're going to work on it, to I don't love you and staying with his friend in a matter of a week. Can someone please shed some light on this situation, opinions please. I'm devastated