have you had a husband that changed their personality following bereavement ?

My husband lost his father (terminal illness) in March 2008. We knew for 3 yrs that he was terminal and that it could be any time. I know this does not make it any easier, and there is no right way to grieve as each person copes differently and you cant judge people. But before his fathers death our marrige was fun, and we were close (he is a quiet person anyway but we were like peas in a pod ) and our sex life was great. Its now 17 months on and our marriage strained and on the rocks and we have become just friends. I have been patient, waited but he has been moody, given up all the hobbies he loved ie mountain biking, and I have not nagged at all, just tried to encourage him to get back to what he loves. But he is more shut off, when the kids are not around he is quiet with me and does not recognise how moody he has been. Our sex life is vertually non existant. I took him away for a weekend just us, and he rejected me. Does bereavement cause such a change in a marriage ? At my families party in May he got drunk and flirted with someone, and was an idiot. I had been in hospital with jaundice due to gall stones for 3 months prior to this party and I felt so hurt that he did this. He has apologised since but my friends think he has been in denial re bereavement and went off the rails . I am a nurse and think he has had mild depression, but he will not listen. He is an only child so it is difficult for him, but surely now is the time to give something back to our marriage ? He does not recognise how he is with others even his friends have noticed and said how quiet and distant he is. What do I do, as I have lost my husband and he is a stranger to me. I have tried everything, even given him space and that has made no difference. He has not mentioned his dad at all and he does not see he has changed. His mother has suggested he goes to the Gp but he is not that depressed that he needs this just is stubborn and pig headed and will not take advise from others.Help ps sorry about long story.