Hurmat-e-Musaaharah

Would a couple be responsible if they don't know hurmat-e-musaaharah was established?

Q: Would a couple be responsible if they don't know that another person has impacted their marriage? For example, (may Allah protect us all from this) if a daughter touched her father with lust but neither her father or mother know about this, would they be responsible? Would the daughter be sinning if she doesn't tell them as it could have disastrous impact on the family? Would her parents be sinning as they don't know? 

Is an erection required for hurmat-e-musaaharah?

Q: A generic question about "hurmat e musahara". I know lust is defined as the erection of the penis. Does slight movement in the penis, similar to what happens during kegel also cause hurmat e musahara when erection does not properly occur/no full erection occurs. I get anxiety and I'm scared. I'm more or less certain that I've never had a proper erection while touching my mother, but at the same time I'm scared of slight movements in the penis that may have occurred in the past - movements that may have occured due to my mental condition. Especially since the idea of potentially negatively impacting my parents is often on my mind when any physical contact occurs with my mother. A slightly detailed and clear answer on this issue could make the matter clearer to me as often I'm not sure what constitutes lust and it makes the matter tough for me. I'd like to think that I do not in any way want to engage in intercourse with my mother and the idea is reprehensible to me. It's after I started reading fatwa on these that these thoughts have significantly started bothering me. 

Touching one's mother with lust

Q: I am 20 years old and I was lying next to my mother while my legs were touching her legs (out of compassion) though I didnt have any bad intentions. Suddenly a very little bit movement occured in my penis. I mean a very little bit erection. I am very worried whether hurmat musahara has occured or not. If it has taken place according to Imam Abu Hanifa (rahimahullah), cant I take a fatwa of other scholars because it will save my family as we have a well established happy family.

Touching one's mother while masturbating

Q: When my friend was 14 or 15 year old, he intentionally touched his mother while masturbating but he is in doubt whether the lust was due to masturbation or due to touching his mother. He has repented from his previous lifestyle. Has hurmat musahara occurred or not?

If it has occured according to hanafis couldnt he take fatwa of other scholars on this because if his father divorces his mother their family will get destroyed as he has other siblings also and they will almost become mad.

Feeling lust when being touched by one's mother

Q: A few months ago after I had returned from a journey to my home, my mother touched me with her both hands on my face and she was crying as she missed me. She touched me 2-3 times and I felt strange and did my best to stop the feeling which might constitute hurmat musaharah. The feeling and notions stopped after few seconds but the private part reached its limit. This all happend within 15-20 seconds and my mother stopped touching me on my cheeks. Does hurmat take place? My parents are of liberal mindset and I'll have to face problems after announcing this. Should I keep quiet? Or reveal this to them?