Alexithymia - difficulty recognising emotional states, including desires, and putting words to them - is a big one.
Open-ended questions are tough as well - i.e. ‘I can’t just come up with reasons why I want a relationship out of the blue - give me a menu of possible reasons and I will answer yes or no’
And then there’s the issue of uncertainty: ‘how can I know for sure whether I want a relationship for the reasons I think I do? How can I know I want something if I haven’t experienced it? How can I prove beyond the shadow of a doubt that something I think I want is actually right for me, or whether the fact that I don’t have it means it’s not meant for me?’ People can go round and round with these sorts of questions their whole lives.
And then there’s difficulty with unquantifiable things / abstract concepts: ‘I’m not sure what you mean by emotional connection - can you give me a very, very precise example, and explain to my satisfaction why it’s a good example? Can you point me to some evidence-based research in this area?’
And then there’s just never having been very interested in relationships in the first place - not seeing the point of fiction or drama / films (apart from genres focussed on problem-solving or world-building), and not having put the hours in observing fictional or real life couples, not having recognised chemistry and affection between people and thought ‘I want that!!’ (But possibly feeling aroused by something they see on screen / IRL and attributing the arousal to some physical detail - what the person is wearing, or the fact she has red hair, etc - and fetishising that)
For a lot of ASD men I’ve worked with there is a sense that ‘getting a girlfriend’ or ‘having a family’ is an achievement you unlock - like beating a level boss in an old platform video game, or obtaining the final item to complete a collection. The acquisition is the whole point. Once you’ve got the girlfriend / wife / kids, it’s done and dusted, chapter closed, time to focus on the next objective.
The fact that the wife and children keep expecting you do to do stuff you don’t want to do even after you successfully acquired them is a frequent source of confusion and frustration.
Some will say, when reflecting on past relationships, things like ‘I get on best with women who have curly hair’ or ‘I have had some success with women who have a masters in a STEM subject’. The success of failure of a relationship is assumed to be based on category attributes of the partner, rather than what happens between them. If currently experiencing relationship difficulties, there is often a lot of rumination about having chosen the ‘wrong’ person on the basis of missing attributes - e.g. ‘I should have known it wouldn’t work out because I’ve always preferred women who are bilingual / high earning / at least 5 foot 7 and I settled for less.’ There is not much sense of a relationship as a living work in progress, so much as a wise or unwise investment in an object.
Bear in mind though that I’m working with a population who have specifically sought mental health support - which means in some cases that they are experiencing significant difficulties in functioning. Not all ASD men etc.