26 year old man dating 18 year old
Just know that it most likely won't be a long term relationship.
Edit: For what it's worth, I don't regret it one bit.
I'm 25(M) and interested in a girl at my job who I believe is still 18. If you're both supporting yourselves, working there, then consider it.
I've had bad experiences dating girls younger than me before. The way I see it is that it merely depends on the person. If she's in high school living with her parents, and you're paying car payments, it might not work.
At 18, I was very mature for my age and I found dating someone older meant we were near enough on the same level. That being said, there's a good chance that an 18 year old isn't going to be too mature, and while it might not seem like a problem initially, it's probably going to start becoming more and more annoying the longer you spend with her.
Whilst I acknowledge that previously you've had issues with dating younger girls, you shouldn't paint everyone with the same brush. Compound her immaturity with having to hang out with her 18 year-old friends, and I could imagine it would be really difficult to deal with.
Have a date if he's interested - don't expect a long term thing, and don't expect it to fizzle out either.
Just be ready to go at her pace, don't expect her to follow yours. If you two mesh well together and you're not her teacher or something, I'd say it's all good. You're not breaking any laws, so the real question is if the relationship works for both of you. We got along great and the age gap was no issue at all.We did get the odd snide comment from people but we brushed it off - we were happy at the end of the day.