Well, if you've got this far you probably know it could be either of you with a problem - or you could just be unlucky with timings etc.
If there's nothing for you that's obviouisly a problkem, like being very underweight, then the quickest thing to do is to is get your other half tested cos you might need loads of tests.
My husband was really keen for children too, so he was just grateful that there seemed to be something we could do when we talked about it and he saw straight away that it made most sense for him to step up and get tested first. His sperm were fine as it happened and it was a big relief (for him!) he was actualy really glad that he tested and got the ok not so he could say well I'm alright, but I think he was pleased to know it.
I think you should more or less come straight out with it and not make a big deal of it, as it's not a big deal, if you tip toe around the subject you might build it up. Or you could take him with you to the doctors as the doctor is pretty likely to suggest he gets tested at least in my experience.
Good luck and don't panic, if he causes a fuss then just pont out to him that the sooner it's sorted out the faster he can forget about it..
Give a glass or two of wine first maybe to unwind him and don't bring it up when he's already stressed out.
Just my tuppneth