Are we from a different generation? I met each of them on OKC, wherein they all answered the match questions, saying that they expect it would take one to two dates to be sexually intimate with someone they really like.
Also, I spent fifteen hours over a week with the one I'm super into before we went to bed. You really don't think that's enough?
Well, hey, look, it doesn't matter whether or not the women you want to fuck are willing to do it on the first or second date or not. I have often done that. But the question is what is affecting you and your erections. I think it's fairly safe to say that for anyone who's been mono for 11 years, fucking someone else/new/different is a complete shock to the system, mentally.
Oddly enough, that was about the length of time I was in my monogamous marriage before it ended. My first sexual encounter with someone other than my husband was quite
disorienting, even though I craved it, wanted it badly, enjoyed it, and have always been (before I was married) someone who has sex very early on after meeting a guy, often on the first or second date.
Obviously, being a woman, I didn't have erections to worry about, BUT it felt like my sexual language, my visceral understanding of myself, how I share my body and communicate physically with someone became completely unfamiliar territory. I was letting someone new inside me, someone who didn't have those old familiar qualities and nuances my hubs had. Several times, my partner would be thrusting away and I would suddenly be overtaken by sobs, there was so much energy and emotion being released. My case was a little different, because my marriage ended and I was still grieving, but it took a long time for me to feel more comfortable with having sex with someone who just simply was not my husband.
I would think the mind plays a part in arousal and how hard you can be. You decided to open up your marriage and immediately, or in a short amount of time (a couple of months?), you have four lovers. Yet you say you want to build relationships. Maybe jumping in the sack right away really isn't what works
for you, when you have the goal of developing a relationship, rather than just getting off. It's not about a generation gap or being modern vs. old-fashioned. Some people just function better sexually if there is some kind of relationship/friendship/connection first.
Maybe you do need to slow down and get to know the person first. Just because you decide to have an open marriage doesn't mean you have to run out and start fucking multiple people right away. There isn't anything to prove. It's not a race, so don't pressure yourself to have a bunch of sex partners before you're really ready. Start with one, cultivate getting to know her, spend non-sexual times with her as well, and don't worry about your performance. When you're in bed together, think about connecting with her through sex rather than just the pleasure of the sensations, and take your time. I think all that might help a lot.