It is virtually impossible for me to accurately explain the true feeling, but it feels very uncomfortable and unnatural to give eye contact, especially with people I don't know well and/or in more formal situations, also the closer the person is sitting or standing to me the more difficult it becomes, it's so much easier to just look away and in my case I usually look downward towards the floor even when I know that this isn't what NTs prefer or expect, unfortunately doing this is giving away that I'm autistic and even NT's who are completely ignorant of autism expect other people to give eye contact in conversation most of the time. If I try to force myself it's really difficult to keep eye contact for long without looking away, if the other person is still giving me eye contact I can almost sense it even when looking away and even this is somewhat uncomfortable, in these situations I will often catch myself fidgeting and stimming by for instance tapping and moving my leg back and forth and/or sometimes my hands which obviously gives away my autism even more.
So why is it so important to NTs to give eye contact in conversations? Well here is a popular answer:
"Eye contact is a form of body language which is important during communication. ... When you keep eye contact with the person you are talking to it indicates that you are focused and paying attention. It means that you are actually listening to what the person has to say."
But I can be focused, paying attention and listening to what the person has to say without eye contact. The way we feel more comfortable having conversations is in my opinion just different, the main issue is when we are being pressured to comply to an NT world.
PS: Wanting to avoid eye contact is a common autistic trait that most, but not all autistic people have. If you're autistic you will also have various other traits, although not everyone with autism has every trait and different traits can be at varying levels. A friend of mine suffers with PTSD after being severely abused throughout his childhood, he finds it very difficult to cope sometimes, but I also strongly suspect he is autistic because he has numerous autistic traits even though he's not officially diagnosed yet. You might want to try the
Aspie Quiz or there's a few other online tests, they're obviously not an official diagnosis, but if you answer the questions as honestly as possible without being biased towards the outcome you want to see they can give you a very good indication, remember that even if you answer some questions against what you'd expect an autistic person to answer, the result could still indicate that you're very likely an aspie. The test indicated that my friend was very likely an aspie as does myself, although I'm officially diagnosed with
ASD and
OCD (please see my test scores in my signature below, the first line is the Aspie Quiz).