"You better not have any sometimes on this bridge. No, let us not talk any more about this bridge. You understand enough now about the bridge. We are very serious so we can make very strong jokes. Look, do you have many girls on the other side of the lines?"
"No, there is no time for girls."
"I do not agree. The more irregular the service, the more irregular the life. You have very irregular service. Also you need a haircut." (1.94-96)
Robert Jordan doesn't exactly start out looking for love. He doesn't want to worry about women. Boy is he in for a surprise. Golz isn't really urging him to look for love. For Golz, women (he refers to them in the plural) are just a distraction to keep one sane in war, probably kind of like food: one has a desire for sex, and needs to satisfy it every so often. With Maria Robert Jordan will find something very different.
She sat down opposite him and looked at him. He looked back at her and she smiled and folded her hands together over her knees. Her legs slanted long and clean from the open cuffs of the trousers as she sat with her hands across her knees and he could see the shape of her small up-tilted breasts under the gray shirt. Every time Robert Jordan looked at her could feel a thickness in his throat. (2.73)
No sooner does he meet Maria than Robert Jordan feels "funny" about her. What he's feeling seems to be almost entirely physical: he's attracted to Maria's physical appearance, and he himself is responding bodily (that thickness in the throat). It's striking how immediate, and powerful, the attraction is. But is there anything here to suggest "love"?
"Then you and me we are the same," Maria said. She put her hand on his arm and looked in his face. He looked at her brown face and at the eyes that, since he had seen them, had never been as young as the rest of her face but that now were suddenly hungry and young and wanting. (6.45)
This is the moment when it first dawns on Maria that she is "the same" as Robert Jordan, which is presumably what leads her to decide to sleep with him that night and convinces her that she wants to "be his woman." It's kind of hard to figure out exactly how she realizes this, since what seems to prompt her to this realization is small talk about how their dads died.
Now as they lay all that before had been shielded was unshielded. Where there had been roughness of fabric all was smooth with a smoothness and firm rounded pressing and a long warm coolness, cool outside and warm within, long and light and closely holding, closely held, lonely, hollow-making with contours, happy-making, young and loving and now all warmly smooth with a hollowing, chest-aching, tight-held loneliness that was such that Robert Jordan felt he could not stand it and he said, "Hast thou loved others?" (7.37)
This is the moment where the barriers come down for the first time. Robert Jordan is bowled over by intense emotion. Interesting that, in the midst of this pleasant entanglement of limbs, he feels lonely. It's presumably that which prompts him to ask whether Maria's been with other men, as if it would detract from his experience with her if she has. (Her answer is no, just in case you didn't see that one coming.)
You do not run onto something like that. Such things don't happen. Maybe it never did happen, he thought. Maybe you dreamed it or made it up and it never did happen. (11.85)
The experience of love is so new and powerful for Robert Jordan that he has difficulty convincing himself it wasn't all a dream. Something about it seems too magical to be real. Certainly in comparison to the dull, duty-bound world he lived in before. He shortly convinces himself it did happen by touching Maria and getting a smile out of her.
For him it was a dark passage which led to nowhere, then to nowhere, then again to nowhere, once again to nowhere, always and forever to nowhere, heavy on the elbows in the earth to nowhere, dark, never any end to nowhere, this time and again for always to nowhere, now not to be borne once again always and to nowhere, now beyond all bearing up, up, up and into nowhere, suddenly, scaldingly, holdingly all nowhere gone and time absolutely still and they were both there, time having stopped and he felt the earth move out and away from under them. (13. 8)
It's that passage that leads to nowhere. This is what Hemingway gives us the second time Robert Jordan and Maria have sex, that time the earth moves (and they make a big deal out of that). If you did want to write about an orgasm in 1940, it's not clear what options you had if you didn't want your book labeled "porno" (like A Farewell to Arms was – check out the "Sex Rating" in Shmoop's guide to https://www.shmoop.com/did-you-know/literature/ernest-hemingway/a-farewell-to-arms/sex-rating.html).
"Maria, I love thee and thou art so lovely and so wonderful and so beautiful and it does such things to me to be with thee that I feel as though I wanted to die when I am loving thee."
"Oh," she said. "I die each time. Do you not die?" (13.13-14)
Love and death. The two things that make any novel exciting, and they're tied together here. Come on, guys, we want more. What does it mean that you "die" each time?
"Now, feel. I am thee and thou art me and all of one is the other. And I love thee, oh, I love thee so. Are you not truly one? Canst thou not feel it?"
"Yes," he said, "it is true."
"And feel now. Thou hast no heart but mine."
"Nor any other legs, nor feet, nor of the body."
"But we are different," she said. "I would have us exactly the same."
"You do not mean that." (20.66-71)
Robert Jordan and Maria both feel that in some way they have fused into the same person, and are no longer separate from each other. This is the deep, profound truth which their relationship reveals, and of course it plays an important role at the end. We think it's interesting that Maria wishes they were exactly the same, though, while Robert Jordan wants them to remain different. She wants to be him, he wants to enjoy her, maybe? Hmmm…
"I love thee as I love all that we have fought for. I love thee as I love liberty and dignity and the rights of all men to work and not to be hungry." (31.96)
Maria now means to Robert Jordan as much as his cause and all the higher ideals he believes in. This creates a tension was not there before in his singular devotion to duty and his casual willingness to sacrifice himself. He's come a long way real fast. So much for not having time for girls.
"Listen to this well, rabbit," he said. He knew there was a great hurry and he was sweating very much, but this had to be said and understood. "Thou wilt go now, rabbit. But I go with thee. As long as there is one of us there is both of us. Do you understand?" (43.319)
In the end Robert Jordan tries to convince Maria to leave him behind by appealing to that sense of unity they'd both felt in their love. He also tells the same thing to himself to comfort himself as he waits alone to die. Death puts to the test all that nice talk of "being the same." It certainly doesn't seem to work very well on Maria.