Okay, people with penises. We've all been there: After a particularly long stretch of only having a fluid bonded partner (someone you don't use condoms with), or possibly just a relationship with your hand or fleshlight* (no judgement, my longest term relationship to date is with my vixskin dildo), your body has forgotten what to do when the most sensitive parts are protected, and you're having some wilting issues while trying to have sex. Don't panic. We got this.
1. Explore a Variety of Condoms: There are SO MANY condom options on the market now. Experiment around while you find what works for your body: I've heard great things about Durex Invisible, and can personally vouch for the heat transfer and good feelings of Skyn brand. Look for things labeled "ultra thin" or "extra sensitive." Some people with penises who don't require XL condoms may find XL condoms a bit roomier and more comfortable, just be sure you keep track of it during sex if it fits you loosely. Internal condoms, sold as female condoms, can be especially comfortable and feel the most like unprotected sex to the person doing the penetrating. They were my favorite as a pro, and I usually pick them up by the dozen whenever I go for STI testing, since they are a bit more expensive than traditional condoms.
2. Add Extra Stimulation: When you put on a condom, add a drop of intensifying gel (I like this one by Kama Sutra, but most 'clitoral intensifying gel' will have the same effect) to the tip. It's important to use one designed to *intensify*, often marketed towards women- the special gels marketed for prolonging or delaying for men often contain numbing agents meant to slow down ejaculation, which is the opposite of what we're trying to accomplish here.
3. Lubricate, Lubricate, Lubricate: In addition to, or instead of the intensifying gel, add a pump or three of a water based lubricant to the tip of the condom before putting it on. I like this kind the best, because it's gentle enough for most skin types. What you're doing here is creating a little, for lack of a better term, 'squelch pouch' as I call it, for the tip of your penis to slide in during sex. Make sure you use a water based lube: in my experience if you do this with silicone lube, it gets *too* slippery and the condom may slide right off.
4. Try a cock ring: Confession time: I have very little experience with cock rings. However, I would be remiss if I wrote a list of ways to help a flagging erection without including one of these handy devices many people love. Cock rings are worn either at the base of the erection, or also around the balls, and help keep blood flow in the penis during sex. There are many styles, materials, and textures on the market, including some that have little attached vibrators for an added bonus during PIV (Penis in Vagina) sex.
5. Change how you masturbate: Do what you regularly do to enjoy yourself, but once your body is well into it and really feeling awesome, pop on a condom, grab some lube, and carry on with exactly what you were doing. Your first few tries may lead to some difficulty, but if you start to lose firmness you can take off the condom and reset. Don't get frustrated: your body is re-learning how to navigate a new sensation, it's going to take time and practice. If you can bring yourself close to orgasm, and have the final hurrah into a condom, in addition to being good practice it's easier cleanup!
6. Change how you think about sex: There's a lot more to intimacy than fucking. If your penis is having some struggles, instead of getting frustrated with it, take off the condom and change activities. Go down on your partner for a while, if you have a fluid bond that includes unprotected oral, ask for oral, mutually masturbate, whatever. You have so many options for exploring pleasure with your bodies together. When you take the pressure off yourself to have an erection, and instead focus on mutual exploration and pleasure, you're demonstrating to your partner your ability to be creative in bed, and that you value their body and sensuality even when your body isn't cooperating.
Thinking too hard about getting or sustaining an erection is the surest way to keep it from happening, so relaxing into the moment and getting comfortable with saying, "hey, can I go down on you for a while? My cock's having a bit of trouble with the condom, but I want to keep making you feel good," may just be the cure your penis needed. I've had multiple lovers where, as we get used to condoms together, sometimes sex happens in stages throughout the course of a date, and while we both like orgasms, pleasure and exploration is the primary goal. This also has the bonus of helping your partner not take any difficulties personally.
I believe in you! Condoms can be complicated to get used to, but with patience and a good sense of humor about it, you're going to be awesome.
* links are affiliate, but to either products I own and love, or totally would put my penis in if I had a penis.