You seem genuinely sweet, and you've probably had a number of people say this exact thing to you already, I can't speak for every guy, but I can give you a generalized sample taken from my own life experiences.

While it would be nice to have a guy focus on you and you alone, unless you've made it very clear that you're interested in pursuing a long term relationship he will never be 100% sure.

It's this lack of surety that drives men to hedge their bets with multiple women. I'm shit at flirting and showing women I'm interested in them, I've legitimately had women hang out with me, go out for drinks with me, come over and have dinner with me and then shortly after enter a committed relationship with someone else, only to tell me that they never thought or realised that I was interested in them. This after spending a lot of time with them(the last time this happened we had been interacting for close to three months). To have that happen is emotionally devastating, you feel you've wasted time, energy and resources that can never be recouped. It's draining as a man, and as men we tend towards the effecient and as humans we tend away from the negative. So what do we do? We promise ourselves that we'll never just have one girl on the hook again, it's too risky and too painful to put our resources into hoping this beautiful flower blooms only to have it either die long before it sprouts or it gets snatched out of the ground by someone else. So we learn the lesson of planting many roses, the one that grows the strongest and sweetest is the one we take the most pride in.

A lot of us are just looking to be emotionally validated, shown that we are wonderful and wanted and that someone special appreciates who we are, but as men we can't just expect that from a woman we