Although he lives a---,he doesn't feel lonely.

alone
alone 指“独自一人的”,如:
He was alone in the room.
他独自一人在屋里.
solitary 指“独居的”,如:
a solitary life
独居的生活.
lonely 指“孤单的”、“孤独的”,如:
He doesn't feel lonely when he is left alone.
在只剩下他一个的时候,他并不感到孤独.
lone 用于诗歌中表示“孤单的(感觉)”,指内心强烈的“忧愁”之感,如:
The lone sentinel walked toward his post.
忧愁的哨兵走向岗哨.
lonesome 指“孤独的”、“寂寞的”,含有“渴望有伴的孤独感”,如:
He was lonesome for a friend.
他孤独,急需找到一位朋友.