I have been dating a guy for six months who is five years younger than me. He lives with his parents. I live by myself.
You are 25, yes? Or will be soon? He is 20 then?
I am going to posit that you slept with a maximum of 3 people this year, one possibly an ex boyfriend, one who you were gonna start something with but turned out to suck/a 5 night stand, and this guy.
The sex with the ex was okay, but it was clear you were growing tired of it, and of each other. While you had been together long enough that he knew your body and could do all the right things, it was lacking in imagination and ultimately unsatisfying, despite whatever "satisfaction"(orgasms!) that might have occurred.
The second guy could go either way. There may even have been more than one of him, dunno for sure, but you don't seem like a "lets bone a lot of different dudes" type of gal. So you went out to try it though, and met this boy, and you banged and he didn't treat you that well. Sex was good though, maybe not because of actual quality, but because you were a little turned on by the fact that it felt a little dirty/wrong. It didn't work out.
This new boy I feel like maybe you have been teaching some things, but shit is probably getting pretty exciting by this point. Like, he is young and full of stamina and excited about the fact that he is banging a sexy older lady, so he is really earnest and psyched and trying as hard as he can to be the best lover ever, but he's not quite there. Probably better than when you started, but some things still make him a little nervous, probably. You probably aren't getting off as much with him as you did the ex, but I could be wrong, I dunno how your junk works really. You could be onea those hair trigger ladies! Either way sex with this boy is probably still exciting at least a little, but not quite as new and fun as it was. Don't let it stagnate like you did with the last boy! Try new things! Go buy some sex toys!
Oh and you fucked him in his parents house, probably drunk, at least once, while they were sleeping and felt really dirty/teenage and youthful about it.