This is not my family, is DP's and I am rather naive to the pain that an OW would cause a family having not been through it myself, so apologies if this post upsets anyone who has.
DP is mid 20s. His parents had an affair then subsequently married and stayed together until he passed not long ago. DP's DM is lovely and I am certain will never meet anyone else as she is still in love with the person she spent 20 or so years with.
DP has half siblings who are, of course, a bit older than him. They have no interest in him and although he says it doesn't bother him I find it unbelievably sad that they don't and he is in essence an only child who has also lost a parent. I can understand their anger at his mother but DP was not the one who hurt anyone and they share a father - it just seems so sad for him.
Am I totally unreasonable to think this? Surely to them it was his mother, not their half brother, at fault so why not pursue a relationship with him?