Really depends on what ages they are/ where they are on the timeline of life as well as how they treat one another. 
Ex. A 30 yo dating a 50 yo is quite different to someone who is say 15 dating someone who is 20 or older. BUT with that being said, once the 30 yo reaches 50 and the 50 yo reaches 70 - they’re at different stages of their lives assuming that the 70 yo is going into a decline and can no longer do the same things he/she once did at 50 but the 50 yo is still relatively active and capable. That can’t be said for everyone though, really depends on the individuals. Some 70 yos could very well still be “capable.”
It does make me uncomfortable to think of someone who’s younger than the legal age of consent dating someone who is like 20+ since 20+ is an adult, who should have a more mature mind, would’ve finished high school a few years ago, perhaps studying in university or working or both, and anyone below the legal age of consent (15-) is technically still a child, school student and minor, not to mention a relationship between the two would be illegal in many places in the world.
Personally, I have no problems with someone the legal age of consent (16 here) dating someone who’s also 16, or 17, 18, even 19 - which might also probably be my limit because they’d be at relatively the same sort of phase in life (nearing high school completion /just starting university) and the years apart are not too vast as well as the fact that it is legal (here anyways) and they’re both still teens.
Of course again, it still really depends on the individuals themselves, how mature each party is, what their intentions are with one another, whether they’re both consenting and respectful and how the older one uses their “power” if they have any.
I hate the thought though of someone young dating someone who is much older or “old” like a 18 year old dating someone who is like, 30, 35+ or 75. Ick.
I’ve seen a lot of older men dating very young women (teens, 20s), particularly in my mother’s home country and it sickened me but it’s quite common there and a lot of them probably perceive it as either the norm or a necessity to survive.
I myself am 23 and I don’t think I would feel comfortable dating anyone older than 28-ish and I definitely would never date someone younger than 18, tbh even 18 is still a bit murky. I view anyone who is still in high school as a kid so I would never consider dating someone who is still in school and nor should I.
Age gaps in my stories
I have an upcoming story actually where the female lead is 16 turning 17 later in the year and the male lead is freshly 19 but they’re both in the same grade since she came over to the US from England, making her a year younger than her classmates and he’s repeating his senior year because he missed it, also making him a year older than his classmates. Despite the gap, they’re still in the same grade and classes. I view it as okay, but someone else might not.
Another upcoming story of mine has a female MC who is 19, one male LI who is 22 and another male LI who is 26 (although I’m considering making him 27) I decided to give readers the option to date someone closer to their MC’s age, someone a little older or no one.
The MC has finished high school but she still hasn’t decided what to do with her life, the 22 yo is/was in university and was largely dependent on his father’s wealth and the 26-27 yo has a 9 yo daughter, a full-time job, a home, but he lost his wife and his son 7 years ago. The guys have vastly different personality and views, so I wanted readers to think about that too and not just their ages.
However, the story is set in a zombie apocalypse and I think when the world is in such chaos and you’re closest to other survivors of other age groups and your own I guess, I think the views on age gaps becomes less pronounced when adrenaline is high and you’ve been through stuff together that people never thought they would like running for their lives, surviving, near-death, grieving, constant danger, always needing to look out for each other etc.
