Anything I recommend, there could be multiple routes, I'm just counting from my own runs of "romance" routes in each game.
S.H.E.L.T.E.R., Zombie's Retreat, Summertime Saga, MyNewFamily (it sort of goes on forever though, but start is really nice,) LongLiveThePrincess (debatable, you sorta do mind stuff to them, but It feels more like unlocking their inhibitions rather than mind controlling them,) Now & Then, Once in a Lifetime, Insexual Awakening, Mythic Manor, Scarlet Law, Heroes Harem Guild, Kindread: The Redburns (memory is a bit foggy exactly on this one, I have a thing for post apocalyptic/zombie stuff and I simply liked the character designs,) What a Legend, Evenicle (I fucking love this game, because it's a pretty all right jRPG by itself and hentai as well, there's a bit of bad guys doing terrible things to women, but YOU do not,) Love & Sex: Second Base, Milfy City (I could be wrong on this one it's been a while but remember liking it, unless I'm thinking of another game with similar name,) MIST, Away from Home, Town of Passion, HS Tutor, Last Hope, Lessons in Love...
That is in no particular order, some I enjoyed WAY more than others. Some were me sort of scrapping the bottom of the barrel as it were, as clearly I got through probably too many of these. Probably some are disputable on whether a character may be as ethical as I would like etc. I have a general theme of enjoying post apocalyptic stuff. I would be happy to answer any questions about individual ones AND would be DAMN WILLING to hear about any other people find that are similar in the whole "actual decent guy has a romantic harem" games that I haven't already consumed. Also I prefer it when the game doesn't start off with the girls immediately throwing themselves at me, I kinda like for it to be a nice romantic build up/work for it to get a bit emotionally invested in it.
Side note, why are all the Harry Potter games always fucking rapey, none of them are romantic and it's never "Harry gets a romantic harem at Hogwarts"? Hear my game devs, make one, please, for the love of all that is horny.