About Ohbas opinion on Lights love life
1.月の異性関係 (Raito no isei kankei) "Light's opposite gender relationships"
2.大学時代の彼女は、カモフラージュを含め, 五, 六人います。 (Daigaku jidai no kanojou ha, camofuraaju wo fukume, go, roku nin imasu) "During university, regards his girlfriends they ARE grouped in five or six as camouflage."
3.でも彼は女性を好きになる事はないでしょう。(Demo kare ha jousei wo suki ni naru koto ha naideshou) "However, he very likely doesn't like any" = 〜事はないでしょう is used for a strong assumption (=most likely it wouldn't happen)
4.対等に付き合える人間はいないし (Taitou ni tsukiaeru ningen wa inaishi) "Equally said, CAN'T date anyone (=any human, as Ohba uses) and..."
5.月も“馬鹿ばかり”と見下しているからです. (Raito mo "Bakabakari" to mikudashi") Light also looks down at everyone thinking they're all stupid (からです= explaining another reason for the above)
6.ただ家族愛とか、人間に対する愛情はあります。友達も結構多いです (Tada kazokuai toka, ningen ni taisuru aijou ha arimasu. Tomodachi mo kekkou ooi desu) But au contraire, with things like family, there are feelings of affection. He also has lots AND LOTS of friends (結構多い).
I've tried to make the translation as close as possible, Japanese is kind of hard because there are nuances you can miss but, they way Ohba uses "human" instead of sometimes "girlfriends" (6) doesn't imply any gender (for light is gay or bi stans). Keep in mind this was written in 2003 Japan, a country that still didn't support feminism and let alone homosexuality (which is still kind of taboo).
Especially Ohba's kind of mysoginistic nature when writing characters so...what HE DID try to say is that he sees girls or anyone as merely humans, something below HIM. Which goes along with the way he's describing KiraLight! instead of YotsubaLight! (which would be a more appropiate way to answer how he truly sees romance).
For some reason he used present tense (1) and I still really can't figure it out, probably has nothing to do but it is kind of curious.
I'D LIKE TO MAKE A SPECIAL POINT ON NO 3
"However, he very likely doesn't like any" = He's using it in present tense, implying that out of those 5 or 6 girlfriends he very likely didn't truly like (or have romantic feelings, not specified).
The fact that he chose that wording says a lot: just because the probabilities are low doesn't mean they're 0.
In 4 he also says he CAN'T, meaning: if he could he would but, depends on who:
Light IS totally capable of feeling love (family), or even developing feelings (I'll make another post about Light regards this, when he first met Misa), although the later is less possible. The reason is just as Ohba stated: he finds the rest as stupid.
Therefore for him to actually consider dating someone it'd have to be at least similar to his level of smart, interesting, someone to keep up with, who challenges him, who teaches him, who makes him doubt...and most importantly, that make him feel human, because he's used to people praising him for being the best and he FEELS like that's his only facade in life, and wants someone to treat him normally without that.
He could also date someone who doesn't meet those standards (see his realtionship with Sayu and Yuri??), although this one is very very unlikely, whilst the other is very much what could happen. At least a 68%, and that's kind of high when it comes to Light.
Now it's true that this doesn't specify what gender Light truly likes, and just because Japan didn't see homosexuality as fine, doesn't mean there were no gays, they were just hidden. But yet again, Light is a fictional character and very highly incredibly likely 99'9999% Ohba imagines him as a heterosexual man, arromantic until he finds someone who changes his mind.