Well what makes being alone equate to difficulty making friends? Is it a causation that because you want to be alone, it affects how you make friends, or is it more of a correlation that maybe being alone may have something to do with the difficulty making friends?
I find that my case is more of a correlation, that I tend to have times where I'm not making many friends, or im not as engaging, due to me wanting to be alone. In that case, I'm ok with that, because I have my seasons I want to be alone, especially with God, and times where I can get up and purposely grow a circle of quality friendships. If that is you, then know that its ok to like your alone time, just as much as enjoying to be around others or being in a relationship. You can easily make opportunities to do either, if you do desire to be among people, or wanting to purposely be on your own.
But if its that you being alone is more of a causation and is affecting your ability to make friends, if your situation is more of a causation, then it would be good to get a counselor or be in a group when you can talk about it and flush out why there's its an uncomfortable idea for you, even if you don't desire it at the moment. Also, getting acquainted with how the Bible addresses how we should be interacting with one another, and keeping our hearts in check, it may help shift how you view different situations such as dating and making friends.