Love spells are not mind control. If a very spiritually advanced person man was out there having full control of women's hearts and minds he desires (or vice versa) thru rituals and spells then it wouldn't be a "love spell" at that point as they would be controlling others against their will.
Real Magick and spirituality has practicality to it but people just see stuff on the screen or read things from people who misunderstand spirituality let alone practice it and believe that's how it works.
Love/sex spells work to open possibilities. Just like money spells. As with the latter you don't have money appear out of thin air just the same as after a few love/sex spells the person you want will not be at your knees begging you to be with them.
The only thing close to the above is if the person was already into you but this is in realistic terms and not some fantasy movie like scene.
As an example, I highly doubt a God will consider it a love spell to seduce someone happily married and with kids and also as humans aren't machines I highly doubt it would work if it was just merely a spell. If a being at that level would do such a thing then that's more along the line of mind control than a spell as it would be against the person's will to do so.
Again, I'm only using this to make a point and not saying our Gods would do such a thing as basically possessing(?) someone to have sex with them or fall in love with them if said person was in a situation where that wouldn't be ideal.
If the mind is open to suggestions then it will receive the energy and the influence will work or won't work depending whatever obstacles there are or lack there of... but it doesn't work like jedi mind tricks.
Any person in general will still have to put in physical "work" after a love/sex spell. They still need to be physically in front of the person and be likable. As with all Magick it just makes it easier for the possibilities to come easier for the person doing them.
All in all I don't see anything unethical about love/sex spells on their own. The ethical parts become relevant depending on the SITUATION, not the spell itself.
Also there will be a difference between doing a spell for someone who is already into you then doing a spell for someone who you barely know. The latter can become a situation where a spell needs to be constantly done especially if there is little to no natural synastry between the two but the spell itself will find ways to make what you want happen even with the possible obstacles.
One can see how the results can be easier to come to if it's done with two people who have good synastry. An example being that opportunities will come to the person doing the spell where they can show the recipient why they are a good match for them.
Lastly, love/sex spells aids greatly someone with really good charm but it makes sense also for people who lack it and need some other type of influence to help them beside their personality or lack thereof.
If the latter is the case for anyone then I recommend building your personality and have confidence in it. The forums has made many posts on how to do this.