That is not correct. If a marriage was never consummated, then it is not a sacramental marriage, and can be recognized as "null." This is true, btw, if the "kind of sex" was contraceptive - because this is contra bonum prolis, and therefore the assocation was not a sacramental marriage. If either party never intended the association to be permanent or exclusive, then it is not a sacramental marriage.
If medical or psychological problems arise, resulting in sexual dysfunction, then medical or psychological help is in order. However, if the problems cannot be resolved - just as with any other medical or relationship problems - this is where you take "in sickness and in health, for better or for worse" seriously, or you're an oathbreaker.
Thank you tax-chick.