Are you trying to say "A long life friend" as in "An old friend"?
If that is so then the word is "Kawan lama". You can replace word "Kawan" with "Teman" or "Sahabat", same meaning there.
Or do you prefer "A life long friend"?
Which translate into "Kawan seumur hidup" or "Kawan sepanjang hidup" or "Teman hidup" (the last one is the more intimate one).

"A man in my life" translate into "Pria dalam hidupku".

If you're trying to use "Sayang" as something to call a person then in a bit similar way you can use "Yayang", "Kasihku".
If you are intending to use the word as an verb then you may use "Cinta".