I think one key to safe sex is just communication. My two married gay boyfriend swing with guys they meet online. They say they really check these guys out first. Chat with them online, get to know them. People generally list their HIV status online. Because I'm very involved with guy men, I tend to be focused on HIV status more that other STDs (aren't all of them except herpes curable?) My naivte here. So, if they meet someone who doesn't use condoms or is positive, they just move on.
I tend to be pretty easily stratified, so I find the more safe sex to be great! Ie, I love kissing, I love being fingered, giving hand jobs and so on. But again, I feel there is always a risk. Always. No matter what.
My husband has had very serious ED since a teenager. He has learned through patience and persistence to use a condom. I don't mean to be cruel, but to a certain extent, that is for the man to figure out, not the lover. I would absolutely not fuck someone because they say I have ED, can't use a condom. For me, for starters, that would put the responsibility of ME exclusively not to get pregnant and that's fucked up. I have empathy for men with ED, but I also am not willing to take responsibility for someone's sexuality. Esp since almost no guy I've been with has ever tried to give me an orgasm! LOL