Marcus was his best friend, his only friend.

They were "pals" and McTeague was very fond of him.

Yet they were both in love, presumably, with the same girl, and now Marcus would try and force the secret out of him; would rush blindly at the rock upon which the two must split, stirred by the very best of motives, wishing only to be of service.

Besides this, there was nobody to whom McTeague would have better preferred to tell his troubles than to Marcus, and yet about this trouble, the greatest trouble of his life, he must keep silent; must refrain from speaking of it to Marcus above everybody.
McTeague began dimly to feel that life was too much for him.

How had it all come about?
A month ago he was perfectly content; he was calm and peaceful, taking his little pleasures as he found them.