We Can't Get Sex to Work?

Married people who were virgins when you got married (both of you): how long did it take you to make sex work? Did it take longer than a month? We just can't make it work and it's SO frustrating. We goes limp at the slightest things going wrong or strange, or he can't come. I don't know what we're doing wrong for the life of me. This is starting to really be a worry. :/ It's like we're doing everything as suggested, we have foreplay, he gets hard, I get lubed up, and then he'll get too sweaty or hot or things get too laughy for a second and then the erection is gone for good. We've had sex successfully only once since we got married a month ago. Someone help :/