Need advice

Ok so I'm 24 and my husband is 26. We have been together for 9 years married for 4 years have two kids together. This whole month he has had issues where we will be in the middle of intercourse and he goes soft or before hand he gets hard then goes soft before we can do anything. I know that he is interested in it because he gets really aggravated about it to but I guess my question is, has anyone else had this happen to their husbands? What is wrong?