Alot of things can cause it.Believe me I know.Im 39 and have been ttc for three yrs now.I jave a son from my frst marriage he is 21.Has your boyfriend been tested?The reason I ask is cause I was on clomid and had iui nothing,i was told I am ovulating.He was told he had a low seman count and motility.The hospital messed up the frst one and said the second one was a 21 million count ,so I made him an appointment the a urologist and he found he had a growth on his urethatube and a seman count and it was 80 million which is a great count.Alot of men like mine dont want to think about it could be them also.So it wouldnt hurt for him to just get tested.My husband is only 29 yrs old.So it can happen to some.