It can take a while for DTD to be comfortable again for a few reasons. The most common issue is being very dry, especially if bfing. Lubricant can help with this, but there is also oestrogen treatment which helps a lot, and is a more long term solution. Your GP or ob should be able to prescribe this for you.

As the others have said, this is very, very normal, so don't feel like there is anything wrong with you. It's really one of those things that should be explained to couples by their Health Professional so that they know what to expect.