I mean... Twilight is one of the best selling novel series of the last 2 decades, and it features a 100 year old dating a 17 year old, and while some people pointed out how uncomfortable it was, the vast, VAST majority didn't care, so I think you're good as far as whether or not this will be a detriment to your readership.
That said, it does present interesting problems and concepts that could make for really good plot fuel. I highly recommend going to watch Star Trek: Deep Space 9 if you haven't. On top of being an incredibly good sci-fi series in its own right, one of the main characters, Dax, is a member of a symbiotic species. Most of them live normal humanoid lifespans, but there's a pseudo-parasitic species of fully sentient and essentially immortal wormslug thingies that can bond with them, bringing along memories and experiences from their past lives bonded with other members of the species.
The character we meet in the show, Jadzia, is the 9th host this particular slug (Dax) has bonded with, and the captain of the station, Sisko, actually knew Dax while it was bonded with the 8th host.
So Sisko goes around drinking and swapping stories with a 25-year old woman, calling her 'old man', and she reminds him of how immature he was back in the day, acting as a mentor figure despite being barely over half his age.
At the same time, though, Jadzia is still present and has her own completely unique personality that gets interconnected with the past lives. She pursues her own romance because Jadzia is still an individual in her own right, and her bond to Dax gives her memories, experiences and maturity that nobody her age should be able to have, but that doesn't overwrite her as an individual. None of the others present view it as an issue for her to be romancing a 30-something year old Klingon because Jadzia Dax is not Jadzia, nor is she Dax, she is a completely unique life form that has her own normal lifespan.
The relationship Jadzia has to Dax's past lives is a major plot point and it's made very clear that her individuality outside of 'being the 9th host to Dax' is something that she, along with ALL of the 'past selves' she has experiences of, values very highly.
The amount of influence the 'past lives' have over the new one is going to be a major factor in your story as far as whether their new incarnation is going to be regarded as an old and wise individual whose experience and age makes it somewhat impossible to pursue a genuine romance with someone so ephemeral as a standard moral, or a new individual who just has access to a far greater library of past experiences and memories than someone their age would normally have.
Additionally, this could be an in-universe conflict. In the anime Dragon Maid, someone asks the almost-immortal ultra-powerful dragon if she can really have feelings for her short-lived mortal girlfriend, and the dragon responds that humans being so short-lived is what makes her love them so much. They are unique and ephemeral, and that beautiful uniqueness ought to be treasured while they exist as opposed to forgotten and written off because they won't be here forever. Similar to how some people treasure HAVING an experience and really being present for it over RECORDING the experience to keep a hold of it longer.
Some of these immortals may consider it creepy or predatory for someone like them to engage in romance with humans, while others might believe that experiencing human life to its fullest (romance included) with each new generation is a valuable experience to keep them from becoming aloof and disinterested in the world around them.
Depending on how much personalities would change from Generation to Generation, the same immortal individual might take a completely different stance on it from one life to the next.
The fact that you asked this question in the first place tells me you're probably thinking enough about it that it won't be a problem. As long as you recognize that it is a situation/conflict that needs to be addressed, the way in which you address it doesn't matter nearly as much. Just make your characters think and act like human beings, and you'll not only handle any potential issues, but also probably create some really interesting storytelling opportunities along the way.