Loneliness and breakups?

I came to the UK 15 years ago for work. I have wonderful kid, job, a beautiful home,quite close friends. After the break with my son's dad I have been unable to form another family.I have had many relationships.none has worked. I have worked on myself to try to smoothe myself out to make space for someone special. But i seem to keep bumping into jerks. So it's just been a collection of disasters. I am fairly active and sociable and do lots of different things gym go out with friends tennis squad hiking climbing. I am not "isolated" but I don't have anyone really close and I miss that enormously. It's really sucking life away. Especially with my kid I need to be happy and steady but this loneliness bleaks everything. It's just not about a man in your life, but feeling connected and rooted. The world seems such a lonely place: anyone in same position? How do you cope? advice? I am 42 I am losing all hopes...