Normally, I would agree but I'm a little unsure with this one. If it was before Karin was introduced then yes, I would have preferred he develop something with Syrup. I'm not the type that thinks "I like a female character so she MUST love the mc" but I do have doubts about most japanese WN authors ability to write an early introduced girl into another relationship or just moving on with their own life and not being a tagalong fangirl. I doubt even more japanese WN readers ability to accept such a scenario.
There was one LN awhile back that I think did it decently that I enjoyed but some readers threw a fit. Boy was isekai'd but before the god could even be seen by him he was LAUNCHED, just straight THROWN as a PROJECTILE into the weakspot of the evil dragon he was summoned to kill, killing it. The girl that was going to be sacrificed then helped him to adjust to the new world, teaching him and introducing him to an older adventurer man (around 25-35 yo) that he became friends with and that man's hot witch mother. His relationship with the first girl ended up as more little brother/older sister and he helps her and her fiancé get together while he goes off with his friend's hot witch mom. I was perfectly happy with this, but some readers just didn't accept that the first girl expressed her gratitude by helping him out and not falling in love with him and the translation died off soon after.