caveat: it is not possible to make an informed comment about any individual marriage situation here. there are too many variables. that is why the person must approach their pastor and ask his help in initiating the process of investigating the marriage. If the marriage is invalid due to lack of form (a baptized Catholic married without following Church laws on marriage) it is a rather uncomplicated paperwork matter, but it still must be done before he is free to marry again. If there are other factors, that have to be weighed, an investigation is done by the canon law tribunal of the diocese who issues a judgement, and if the marriage is indeed invalid gives a decree of nullity to ratify that judgement. Both parties are then free to marry (the status of any children of the marriage is unaffected).
Whether the Catholic has been confirmed or made first communion is not an issue. A baptized Catholic is bound by Church laws on marriage unless he has formally renounced the Catholic faith. If he marries without following those laws his marriage is not valid. It is hard to see how he would have been allowed to marry in the Catholic Church without first completing his Christian initation sacraments, but it could happen. If so, and the conditions for valid marriage were otherwise present, he is still married and not free to contemplate another relationship until this matter is resolved and a judgement made by the tribunal.
please search the appropriate forum, liturgy and sacraments, under annulments to turn up several threads on this topic with very good links.
