Let me ask you something Guy.
You can suspend disbelief that ships can travel a thousand times the speed of light without time dilation. You can suspend disbelief that we can instantly transport matter from one point to the next. You can suspend disbelief that ships can travel at multiples of the speed of light and still not only see each other on the viewscreen, target each other with weapons. You can suspend disbelief that omnipotent energy beings can snap their fingers and vanish stars out of existence, and that these beings spend their time messing with us. And you can suspend disbelief that no warlike culture in the universe has ever considered building a fleet of millions of small, mobile fighters, rather than do all their fighting in large bulky submaries.
But you can not suspend disbelief that in a fictional universe, machines can experience sentience, and the very suggestion that they fictionally can bothers you intensely.
I imagine that although Neelix and Kes did not have sex they did participate in lesser romantic activities. Remember he's a TV character, TV characters don't experience sexual desire until they are deeply in love with a person they want to spend the rest of their life with and want to produce children with this person. And any characters who violate this trend are considered scumbags.