It is difficult because we're not supposed to be living like we think our spouses might be undercover agents for another country. We care for them. If they say they're sick, or have ED, needed to work late constantly, spend hours at the gym, etc. we believe them. Until we have a reason to no longer trust them, but we're generally not looking for it. 

If you want the perspective of someone who lived a double life, you might want to post some of these questions on Sean's thread. However, there are numerous cases detailed here from people who had a spouse living a secret double-life, sometimes for decades. Clarification and truth from the in-denial spouse sometimes never happens. You need to decide when you know enough. Decide on the future you want and start taking steps towards it, even if they are small ones. Don't let the distance dissuade you. All journeys start with a first step.

Confusedpartner - I can't speak to all of your questions but I can share my experience on some of them:

 Does gay in denial husband could act like a straight man in physical intimacy?

Absolutely!  I was married for almost 30 years to a man who I thought was straight.  We had frequent (several times a week if not daily, and every once in a while multiple times a day), satisfying (I thought), fun, sex that (again I thought) was intimate.  There were never red flags I've read in others' experience for me to pick up on even in retrospect.  

Is it possible they could seek sex with men outside hidden from straight spouse?
Again - absolutely!  My exhusband was on Grindr and Sniffies constantly and engaged -during COVID when we were together with our kids and their friends 24/7 at our house- in sex with men in public restrooms, parking lots, on bike trails, in my car, and in my bed.  It blows my mind looking back at how he pulled it off.  If he had a dentist appointment that I didn't go with him to, he fucked someone in the bathroom, a run to grab a bottle of wine?  In the parking lot.  A quick bike ride by himself?  Yep on the trail... There is no limit to what they can look you in the eye and say while planning and maintaining their selfish, secret lives.  I had no idea - again this is when we were literally in the same house constantly, not "normal" when he was going to work at the office with all sorts of other opportunities.

 Can it be hidden to this extent?
Again - YES.  And my exhusband was so full of integrity and amazing and I loved him with all of me.  Everyone thought of him as honest and the "perfect" man in all respects.  He is NOT THE MAN I MARRIED and NOT who he portrayed himself to be.  He chose himself above me and my kids every single time he had the opportunity.

Any insights? 
Honestly, I wish I had not held out hope and thought that OUR marriage was DIFFERENT.  That WE could make it work, that he just had struggles and POOR him.  I wish I consulted an attorney and had my exhusband sign a post nup agreement before it all went to hell so that part of the horrendous experience was eliminated.  I wasted YEARS of my life trying to make it work and be there in support of him.  Get tested for STDs regularly even when he says he is not cheating or if you cannot bring yourself to ask him.  It's a humiliating experience each time but worth doing.  Message me if you need, this forum is a life saver to read through what others have gone through.  I know this all sounds negative, but those are the honest answers in my experience to the questions you asked.  A "hug" from me, I'm sorry you are having to ask these questions on our forum. - "Marie"