But no, he would not give in. Turning sharply, he walked towards the city's gold phosphorescence. His fists were shut, his mouth set fast. He would not take that direction, to the darkness, to follow her. He walked towards the faintly humming, glowing town, quickly. (15.148)
In these final moments, Paul has just walked Miriam home and decided (for the hundredth time) that even though he loves her, he can't be with her. (Single tear.) At this point in the novel, Paul's in mourning over his mother's death, and he's been in a bad way—he's been spending most of his time knocking around the local pubs and flirting with randos every night.
After this final break with Miriam, Paul knows that's he's destined to feel empty. He's so lonely without his mother around. So he starts to wonder about committing suicide, which would reunite him with his mommy, after all.
At the last second, though, he musters enough strength to decide that he won't give into the pain of life. He want's to live. Dude's gonna stand up and keep fighting, okay?
The fact that he turns back to the "glowing town" in the final line shows that he's ready to go rejoin the world and be happy. Well, um. Maybe. The problem is this: we've seen Paul make this exact same kind of resolution a dozen times—ditch the girl, get a life of my own, blah blah blah.
So if the rest of the book is any indication, Paul's probably going to run back to Miriam another thirty times before he dies. And those two lovebirds will keep playing the same "will-we-won't-we?" game over and over again.
In a nutshell, Lawrence is probably admitting here that there's no clear answer to a dilemma like Paul's. For Lawrence, the contradiction between wanting to bond with someone else and wanting to be completely alone to pursue one's deepest desires lies at the heart of almost every person… especially young men like Paul.
The ending of Lawrence's book suggests that it might be impossible to overcome this conflict. Nevertheless, it's important to try to keep on fighting, to keep on living.