Divorce, unworthy reception of Communion and gay marriage are not settled teachings, not anymore. Indeed, the proof texting on each is obviously flawed and because we can now read the bible in English, we can raise these questions.
The question is not whether grace can overcome the need to Marry again but whether it has to. If the Church has been proof texting Mark inaccurately, which on its fact condemnds divorce and remarriage as a single act (i.e. divorce not and but to marry another), then there is no need for grace.
Not adultery if you were the one who was dumped and then remarried. As for gays, if they were born that way, married homosexaul relations cannot be sinful. The sinful act of sodomy was pederaasty.
Again, no sin, no Communion problem. Also, when Paul wrote, there was no doctrine on mortal sin. Being unworthy was receiving but not believing.
If you can follow my logic, which is the truth, then you don't need to bother the Holy Father, especially after retirement.