Happened with two guys before I came out as bi, and with several more since.
Before I came out, two stories:
1. My straight best friend/teammate in high school and I used to send each other videos of the porn we were watching on our laptops through Snapchat, and, over time, also pics of us fully nude (mostly in a joking manner, doing something stupid while naked, or complaining about how hard we always were). A few times, when we travelled together for sports, we jerked off next to each other in the same bed under the sheets watching porn on my iPad that was between us. We had always changed together for competitions so seeing each other naked wasn’t new, only seeing each other fully hard. Looking back, I should have known I was into dudes at this point but was in pretty heavy denial. I always wanted to and kept trying to see his dick and I was way too willing to show him mine to be straight. We barged into the bathroom several times on these trips while the other was showering (some of my other teammates joined in, too) and recorded ourselves dumping ice water on whoever was in the shower. On one of those trips, he screenshotted a pic of my cock from one of the shower videos he took and it wound up on our team’s group chat on our return flight. No doubt some FA caught a glimpse of my cock at some point. There was a period of about a year between the last time we jerked together on one of those trips and the time that I told him I was bi. We got even closer throughout the jerking we did together, and we were definitely able to tell each other things that no one else knew. All that ended when I came out to him, though: we still haven’t spoken again since that day. He blocked or unfollowed me on everything, probably fearing that our community wouldn’t accept him if he stayed friends with me once others started to find out. Shitty situation but, for the purposes of this story, we did jerk together before I came out over the course of about two years and it intensified our bond. He was two years younger than I was and I considered him a little brother because of how close we got.
2. During undergrad, one of my mentors (in his late 20s) that I had known for about a year randomly told me in private that his wife wouldn’t let him jerk off at home, and that anytime she suspected or caught him, he got into trouble. Fast forward through a week or two of us talking about sex techniques, previous sexual experiences, what we enjoy sexually, and what he’s learned about dating a woman long-term and eventually marrying her, he popped the question of whether we can jerk off together in my dorm room since he couldn’t at home. After some back and forth, and a lot of hesitation on my part, I agreed and was very awkward the first time. I was out to a lot of people at this point, but not to him until after we had jerked together a few times. I was worried that my sexuality would affect our mentor-mentee relationship even though we were jerking together, but, at the end of the day, he took it very well once I told him. The first time he came over, I had porn on but neither of us really watched it. I kept trying to talk to him about the scene, but he was fascinated by my cock. Specifically, he couldn’t get over my thickness or the size of my head. Because I was still new to jerking with guys, I went pretty soft as he stared down my cock and kept talking about it. I was hesitantly laughing, and I asked if I could touch his. I wound up jerking his dick for a few minutes until he said he was getting really close out of nowhere. He had tried to work me up as I was jerking him the whole time, but nothing came of it. He told me to stop stroking him because he wanted us to cum together, so I wound up turning the porn off of the TV and watching something on my phone as he laid next to me. Mind you, this is a twin bed in a college dorm room. It was a small space and he could see everything I was doing and watching still. After another 5-10 minutes, I had become focused enough to work past the nerves and got fully hard. Hesitantly, I told him that I wanted to feel his dick as he came, and he told me to touch it again. As soon as he did, he blew a thick load all over his stomach and let out the most relieved-sounding exhalation that I had ever heard. It had obviously been a while since he had been able to jerk it in peace. I took the same hand that I used to finish him and finished myself off, with him encouraging me along the way, saying things like “fuck yeah bro” and “make that grip tight man.” We had a few meetups like that until we started frotting, again at his suggestion, and that continued for about two months until I told him I was bi. Each time we had met up, he left very quickly because he always told his wife that he was running errands, so he couldn’t stay and extend the time. A little more background: this guy had some experience. He knew how to ask me whether we could jerk together, knew what he wanted, and was super comfortable touching each other’s dicks and frotting. He still identifies as straight to this day, but he enjoys some stuff with dudes. There was a point that we stopped meeting up frequently because of our schedules, I was in a new relationship, and then, soon after, I moved. But, we still talk sometimes, he still asks me to show off for him online, and he’s still with his wife. He just enjoys stroking it and frotting with the boys. We trusted each other quite a bit after we started frotting and once I came out to him, but the limitations of the time we could spend together hanging out because of his wife (and kids) limited the bond we could develop. Most of the times he came over, he just wanted to jerk. Lesson from this story is that jerking together is cool, but you need a solid friendship, too, to get after a completely fulfilling jobud-friendship.
After I came out: I’ve had some really great experiences and developed a lot. With guys, jerking and frotting have become two of my favorite sexual activities. I’ve jerked it with plenty of other dudes that I’ve gotten to know (most of whom aren’t straight), but some who are. Some of my guy friends from before I came out also got very comfortable showing me their hard dicks over snap, asking me to give them “feedback,” etc. Having played sports most of my life, it was always pretty normal to see each other naked in most of my friend groups. So, nudity never having been an issue, some of the guys I was close with at different points in my life have taken advantage of that.
My (definitely straight) closest friend in grad school (whom I’ve been out to since the day we met) snaps me pics of his cock all the time. We never make too big of a deal about it — he finds it really comfortable to show off online to me (he doesn’t in person at all, though), and I’ve sent him full nudes of me back. He hears about a lot of my sexual experiences as they happen since we’ve stayed very close since graduating and he’s seen vids of me doing various sexual activities with both guys and girls. The guy-on-guy stuff he watches out of pure curiosity; the guy-on-girl stuff he, no doubt, faps to. Being able to share everything together—from unexplained sensitivity on his penis at one point to cock pics to career advice—has made him and keeps him as one of my best friends.
(tldr) All in all, to answer your question: yes, jerking with another dude strengthens the relationship. Above, I focused on examples from straight guys that I’ve jerked with, but the same is true for queer guys and NB people. I’ve gotten very comfortable with some gay/bi guys, for example, whom I jerk off with on occasion to this day. For me, jerk buds are a positive component of some of my friendships and help to forge intense bonds. Feel free to leave any questions below if I missed details.