What passages in the chapters 7, 10 and 17 of Frankenstein could make us think it is a Romantic story?

There are many passages in Chapters 7, 10, and 17 that characterize Frankenstein as a Romantic story.
Romantic literature particularly focuses on the following:
feelings of deep melancholy
frequent introspection
emotional intensity: anger, fear, and sadness
a reverence for nature and its destructive power
the value of the subjective over the objective.
Take, for example, the following passages from Chapter 7:

My journey was very melancholy . . . Fear overcame me; I dared not advance, dreading a thousand nameless evils that made me tremble, although I was unable to define them.
I remained two days at Lausanne, in this painful state of mind. I contemplated the lake: the waters were placid; all around was calm; and the snowy mountains, “the palaces of nature,” were not changed. By degrees the calm and heavenly scene restored me, and I continued my journey towards Geneva.
Yet, as I drew nearer home, grief and fear again overcame me. Night also closed around; and when I could hardly see the dark mountains, I felt still more gloomily. The picture appeared a vast and dim scene of evil, and I foresaw obscurely that I was destined to become the most wretched of human beings. Alas! I prophesied truly, and failed only in one single circumstance, that in all the misery I imagined and dreaded, I did not conceive the hundredth part of the anguish I was destined to endure.
The most violent storm hung exactly north of the town, over the part of the lake which lies between the promontory of Belrive and the village of Copêt. Another storm enlightened Jura with faint flashes; and another darkened and sometimes disclosed the Môle, a peaked mountain to the east of the lake.
While I watched the tempest, so beautiful yet terrific, I wandered on with a hasty step. This noble war in the sky elevated my spirits; I clasped my hands, and exclaimed aloud, “William, dear angel! this is thy funeral, this thy dirge!”

Here, Victor alternates between grief, anger, and fear. His misery is palpable, and the intensity of his emotions clear. In the above passages, Shelley also portrays nature as both flawless and formidable in nature. Tempests and storms, so prevalent in Gothic and Romantic literature take center stage in Chapter 7, as Victor confronts the possibility of the monster's culpability in William's death. The powerful storms certainly mirror the intensity of Victor's emotions, and they seemingly validate his right to experience their weight.
Here are similar passages in Chapter 10:

They congregated round me; the unstained snowy mountain-top, the glittering pinnacle, the pine woods, and ragged bare ravine, the eagle, soaring amidst the clouds—they all gathered round me and bade me be at peace.
Where had they fled when the next morning I awoke? All of soul-inspiriting fled with sleep, and dark melancholy clouded every thought.
The sight of the awful and majestic in nature had indeed always the effect of solemnising my mind and causing me to forget the passing cares of life.
I looked on the valley beneath; vast mists were rising from the rivers which ran through it and curling in thick wreaths around the opposite mountains, whose summits were hid in the uniform clouds, while rain poured from the dark sky and added to the melancholy impression I received from the objects around me.

Again, the theme of nature as both an ennobling and formidable presence is acknowledged. Intensity of mood is mirrored in the elements of nature. Yet, nature is also seen as a means of transcending the corrupt, primitive nature of humans. Victor certainly relies on nature to bring him to a state of emotional equilibrium.
However, his introspective thoughts continue to consume him, and he can't stop thinking about the monster he created. When he does actually confront the monster, Victor unleashes an unmitigated fury of emotions against it. Here, the Romantic focus on intensity of emotion comes into play. One's natural feelings are prioritized over controlled rationality. This too is the trademark of romantic literature: the subjection of the rational to the visceral.
You may be able to identify similar passages in Chapter 17.