The problem is, especially for new couples: If your dick don't work, self esteem plummets. The guy usually feels like the MC does and the gal could feel hurt that maybe she wasn't X enough if/when they discover it. The reason aside it hurts both parties nonetheless and is very difficult for the couple as a whole.
Can confirm that dick failures early on in a relationship can be very harmful for both parties. Did the whole loop from premature release causing such low self esteem that for the next few weeks that I couldn't even get started. The missus thought it must be something wrong with how she looked or her feeling like she lacked skill.