Should I Accept His Marriage Proposal

I am 41 years old. I have been living with a widower for 5 years. More precisely, he lives with me and my son. His daughters are older - one is married and the other is abroad. Strange problems come from them. Apparently they can't accept that their father can live with another woman. She died 11 years ago. During this time we were together we built a house in the yard of his late wife. His children's house. Everything was fine while we were building and repairing the yard. Now I began to disturb them clearly. We have met and parted several times. Now, however, I do not go with him to the village, and his children told me that they wanted me to go there to help them .... I am sorry that during the weekend he is in the village, and I alone with the dog. My son goes to his father. He wants me by his side, but his children bother me. They behave in our house as if I were a guest. This irritates me a lot. We talked about it with the man next to me and he said he would make things right. However, I am not convinced. As far as I understand, he seems to want to propose marriage to me. What to do? I care about him, but his children ... They are big and don't look after their lives, family, men ..., but dad. Advise me what to do. I am very confused. Can he really change that attitude towards me? Should I trust him? I only have problems with his daughters. We get along with all his relatives. They accept me quite normally, but these children .... I only have problems with his daughters. We get along with all his relatives. They accept me quite normally, but these children .... I only have problems with his daughters. We get along with all his relatives. They accept me quite normally, but these children ....