One thing you could try, if you haven't, is dating someone you connect with, and have a fun time with, even without "romantic spark". Attraction can be important in a relationship, but in a long term relationship spark often doesn't last anyway, and it's other things that actually keep people together. Getting along well, working well together, handling stress in complementary ways, etc, are all more valuable long term.

So just as an experiment you could try dating someone for something "long", but not actually that long in the grand scheme of things. Maybe 3 months, roughly one season. Even if you're not physically attracted to them, try dating them anyway. If it doesn't work, you haven't actually lost anything. Just a bit of time. And you will have officially "had a girlfriend", and gained some amount of relationship experience, even if it wasn't the best.

And if it just so happens that you're just not an "early term" guy, buf you're actually a pretty good "mid-term" guy, then that's great! Keep going! You haven't got a lot to lose, in a sense, so you're available for experimentation.

Well I would say for a start that while you say you're ugly someone will think you're pretty. The thing is one of those people should be you. Anyways, I wouldn't call it inceldom, if anything just a mild lack of self-esteem, that's fixable, how depends on you tbh, I personally recommend going to the gym because it worked for me, even without much gains it helps a lot with confidence, especially if you compare yourseld only with your past self and not others. Of course it may or may not work for you. Once you figure out why you feel ugly and work through it, giving yourself time to adjust and not being too harsh on yourself while trying to still maintain some discipline, you will probably realize you aren't as ugly as you think you are and maybe one day find someone you like. Or not, well at least not for a while, but at least you'll be happy even if single

First of all, most people are their own worst enemies, because you have to live with yourself, and you know exactly where your weakest points are to emotionally punch. So chances are you're more attractive than you're giving yourself credit for.

Secondly, your body is not static. You can really be whatever you want to be, and if your body isn't in shape now you can get it into better shape, and probably into better shape than it ever was before in your lifetime. There is certainly a genetic and birth lottery for how easy your goals are to achieve, but they do remain ultimately achievable. I personally felt like as a nerd I couldn't choose to be physically active, that I had to pidgeonhole myself into a stereotype, which is very not true.

Thirdly, whether or not you're super hot in reality, getting your body moving is freaking amazing for your mental and physical health, and once you can start hitting milestones your past self never could have its incredible. I literally could never do a pullup when I was younger, but now I can do pullups. And that took literally 2 months of 20 minute workouts. So pickup even a basic 5 day at home workout regiment, or bike every evening or run every morning. Seriously the healthier feeling from actually moving vs. being a lump is amazing

Finally, the bar is so freaking low for dudes. If you can be confident and not a douchenozzle and have decent lifeskills I guaren-fucking-tee you there is a woman out there who is perfect for you and far more interested in that criteria than simply finding someone who's conventionally attractive with social traits that they can put up with.