I've developed feelings for my friend of more than ten years. Should I continue? Thank you, everyone.

Many so-called friends of the opposite sex became friends because they liked each other back then. I'm no exception. He had been with her for 13 years. From having a crush on her, to breaking up with her, to becoming friends again, to asking her cohabiting partners out for dinner, to being single and ambiguous now. Of course, neither she nor I were rational enough to cross that line. Because he knew very well that friends were hard to find, and the opposite sex was everywhere. However, now that they were at the age of marriage, they realized that other than the other party, it was very difficult to find two people who could get along so well. She now thinks that I'm a very suitable marriage partner for her, but it's very difficult for her to have an electric shock towards me. On the contrary, I feel that my personality isn't very suitable because the two of us are too domineering. However, I still have an intermittent electric shock towards her. If we were to go back to a few years ago, we would have been together regardless of everything. Unfortunately, we didn't feel anything back then. The problem was much more complicated now. She was already at the age of marriage. I couldn't be irresponsible and have a crazy relationship with her. Although I really wanted to do this, my rationality kept reminding me that when two people lived together, the feeling of hanging out with friends was completely different. Now that he was with her, if they broke up in the future, he would not only lose his lover, but also lose his lifelong friend. Actually, I'm also an expert in relationship theory, but I can't find a way out of this rare problem in this world. I hope everyone will give me more advice. The score doesn't matter to me. I can give you as much as you want. If you have the same problem as me, I look forward to your valuable experience. Thank you very much. Those who agreed to be together had an overwhelming advantage. And I'm especially grateful to flyhc918 for his precise comment on me,'Love coward.'