"Love your fellow as yourself" and seeing your future wife before marriage

The Talmud in the beginning of the second chapter of Kiddushin (41a) states that one must make sure to see his future wife at least once before he marries her - lest he marry her and find her unattractive to him.

Soncino translation:

 MISHNAH. A MAN CAN BETROTH [A WOMAN] THROUGH HIMSELF OR THROUGH HIS AGENT. A WOMAN MAY BE BETROTHED THROUGH HERSELF OR THROUGH HER AGENT. A MAN MAY GIVE HIS DAUGHTER IN BETROTHAL WHEN A NA'ARAH [EITHER] HIMSELF OR THROUGH HIS AGENT.

If he can betroth THROUGH HIS AGENT, is it necessary [to state] THROUGH HIMSELF? — Said R. Joseph: [This inclusion intimates that] it is more meritorious through himself than through his agent... Some say that in this matter there is even a prohibition, in accordance with Rab Judah's dictum in Rab's name; for Rab Judah said in the name of Rab: A man may not betroth a woman before he sees her, lest he [subsequently] see something repulsive in her, and she become loathsome to him, whereas the All-Merciful said, but thou shalt love thy neighbor as thyself.

The gemara uses the verse "You shall love your fellow as yourself" as a proof for this. The verse can be used in two ways toward this, in my understanding. Either, 1) it will hurt her feelings if you can't find your wife attractive, which is not how you would want to be treated as well. Therefore, you shall love her as yourself and preemptively make sure there will be no problems like that. This understanding would mean that it would violate the command of loving one's fellow to not look out for the possibility of future hurt, even if it is understandable once you're in that situation. Or, it can mean 2) that in this instance, the gemara is using the verse on a very literal level. You shall love your fellow as yourself - if you don't find your wife attractive, it means you won't love her as you would want to be loved by her, a violation of the literal expression of "ahava" the verse uses.

Be that as it may, it is curious to me that such a broad verse about being nice to others is being applied here. It makes sense according to my second explanation, but for the first, what is the connection between the broad verse and the specific case?

The Baal HaTurim writes something interesting on "You shall love your fellow as yourself." He is trying to solve for the apparently arbitrary juxtaposition of this commandment and the prohibition of forbidden mixtures, kilayim, that you shouldn't create a new animal by mixing two different ones.

He points to two different Talmudic passages, as sourced by the HaMaor Mikraot Gedolot Chumash:

וסמיך ליה לא תרביע כלאים האוהב אשתו לא ישמש עמה ועיניו באשה אחרת ולא יכפנה לתשמיש:

It juxtaposes it to "Do not mate different animals...", [because] one who loves his wife may not have sex with her while his eyes are on another woman (Nedarim 20b), and he may not compel her to have sex (Eruvin 100b).

Meaning, that when a man has in mind another women while having sex with his wife, or when he is violating both "love your fellow..." and "kilayim" (the latter in a metaphorical sense).

The quote from Nedarim 20b goes:

"And that ye seek not after your own heart." [Deducing] from this Rabbi taught: One may not drink out of one goblet and think of another. 

(Also see Bamidbar Rabbah 9:34 - אָמְרוּ רַבּוֹתֵינוּ בִּזְּמַן שֶׁהָאִשָּׁה מִיַּחֶדֶת עִם בַּעֲלָהּ וְהִיא מְשַׁמֶּשֶׁת עִמּוֹ וְלִבָּהּ לְאִישׁ אַחֵר שֶׁרָאֲתָה בַּדֶּרֶךְ, אֵין לְךָ נִאוּף גָּדוֹל מִזֶּה, שֶׁנֶּאֱמַר (יחזקאל טז, לב): הָאִשָּׁה הַמְנָאֶפֶת תַּחַת אִישָׁהּ תִּקַּח אֶת זָרִים, וְכִי יֵשׁ אִשָּׁה שֶׁמְנָאֶפֶת תַּחַת אִישָׁהּ, אֶלָּא זוֹ הִיא שֶׁפָּגְעָה בְּאִישׁ אַחֵר וְנָתְנָה עֵינֶיהָ בּוֹ, וְהִיא מְשַׁמֶּשֶׁת עִם בַּעֲלָהּ וְלִבָּהּ עָלָיו. )

The implication in the discussion after this is that the such sex will result in blemished children. Presumably, the Talmud believes in the concept common then (and is even held by Shadal in the 18th century in Jacob's tricking Lot and achieving the kind of sheep he wanted) that thought during intercourse affects the offspring of that coitus. By thinking of another woman, the Baal HaTurim is saying, one engages in the creation of a new species that shows his lack of love for the wife he had sex with. Relating this to the passage in Kiddusin above, one can see how someone who does not find his wife attractive would violate loving one's fellow as oneself, when that verse is related to how one should not imagine another woman when having sex with her. If he is disgusted by his wife's appearance after he marries her because he didn't know what she looked like before, he will be forced to think of someone else when he wants to perform the commandment of peru urvu.

The Baal HaTurim also reference Eruvin 100b:

Rami b. Hama citing R. Assi further ruled: A man is forbidden to compel his wife to the [marital] obligation, since it is said in Scripture: And he that hasteth with his feet sinneth. R. Joshua b. Levi similarly stated: Whosoever compels his wife to the [marital] obligation will have unworthy children.

Baal HaTurim is saying that this is another case of not loving one's wife and forcing her to create kilayim, unworthy bastard children. Again, this is related to one's love of wife, but not necessarily with how much he finds her attractive. Still, the Baal Haturim's first comment is helpful for us.