there's no way to answer this without sounding a bit crude.
Are you relaxed enough, sometimes you might need to use extra lubrication, can you use tampons ok, sometimes if you can't that might be an indication you might need to visit obgyn.
Is your relationship with your husband otherwise ok?
If so I would pay a visit to an obgyn and just ensure everything is ok.
It can be stressful if physical things aren't going well, which only adds to the problem.