by nature, bettas don't get 'lonely'. that's not to say they're not social, they just don't want any other bettas in THEIR territory. if you want to get two, get two different tanks, or a 5 gallon and divide it. my own bettas live in their own tanks, and three of them are side by side, so they can see another betta whenever they want. even my delta tail doesn't tail bite, and my shy little HMPK's getting some courage by 'scaring off' my delta and female PK(more like old lady Lulu gets tired of his antics and swims away, and Ichi gets bored of watching him show off and goes to rest in his plant. xD).
if you want multiple bettas in teh same tank, as i said, divide a 5 gallon or larger, or get a 10 gallon or larger and start a sorority.