I would like to inscribe this on my gravestone, in Latin: "in love and friendship forever." Could someone help me translate it?
I was originally going to suggest the same-ish answer as @TomCotton. However, since he has provided it already I am going to simply provide some suggestions concerning orthography, rather than translation, given that the phrase you requested is going to be displayed.
Classical Latin, at least when it was carved into stone (you indicated in your question that this was going to be engraved on a gravestone), typically carried the following characteristics.
- Written in all-caps.
- The letter U was written with V.
- Dipthongs ae and oe were often written as single characters.
- Instead of simply spacing words, they were often marked with an interpunct character, or the spaces were simply left out.
- Long vowels could be marked with apices.
With all that said, the wonderful suggestion from @TomCotton could be rendered as such