Talk:A Discovery of Witches (book)/@comment-38892727-20190527202232/@comment-30796761-20190606064717

Diana and Matthew themselves did address in the first installment just after they touched each other for the first time:

"If it is magic, then I'm even more delighted to be sharing the rest of my life with a witch" he said sounding as content as I felt.

''"You mean the rest of my life not the rest of yours." ''

''Matthew was suspiciously quiet and I pushed myself up to see his expression. "Tonight I feel thirty-seven. Even more important, I believe that next year, I will feel thirty-eight."''

''"I don't understand" I said uneasily. ....''.

"My life now has a beginning, a middle and an end. Everything before was preamble. Now I have you. One day you will be gone and my life will be over."

''"Not necessarily" I said hastily, "I've only got another handful of decades in me---you could go on forever." A world without Matthew was unthinkable.''

"We'll see" he said quietly, stroking my shoulder.

''pg. 362-363 paperback''

What he's established here is that as far as he's concerned his time with her will be his lifetime that before her his physical existence was fetal and after she's gone it will go into a metaphorical stasis. He also implies that he will find a way to achieve suicide. Difficult is NOT impossible and the only difficulty he can't handle is NOT being with her. That's where this all started in the first place.