Okay, regarding the age issue. Yes, it can be irritating if you're into age gap and people always keep coming in to say "adults and kids in relationships is wrong!" It can be really hard to see something you enjoy criticized, and you are likely tempted to lash out at them.
Thing is though, 15 really is a child still. And the difference between that and a 30 year old adult is pretty vast still. And if you're a fan of age gap, you're going to have to accept that you're a fan of a controversial subgenre that incorporates something unacceptable in real life. You can claim "it's fiction" all you want, but this is the price of admission, the same as it would be if you were a fan of rape stuff or vore or something. It's what you should expect coming in, all the more when the age is low.
As to the story itself, honestly it doesn't come off as much of a romance to me in the first place. The girl's cofession aside, it otherwise seems pretty bloodless. Her feelings, by her own admission, are based entirely on "you're the only one who was nice to me", while the older woman doesn't seem to have any particular strong feelings at all and has to be convinced into it. She's not looking for romance, and aside from the Magic Kiss That Stirs Feelings™ still doesn't seem to have found it. I guess it would be a cute one-shot, and we've got other ones that run like this on the site already, but I just ain't feelin' it as a couple I want to root for.