Since the singer, 26, finished her "1989" world tour late last year, she has moved into 31-year-old Calvin's Beverly Hills home, reported E! Online.
"Now that her tour is over, they are living together at his house in Beverly Hills while she is having some work done on her new home.
"They are definitely talking about their future together and the possibility of one day getting engaged. Making it work, despite their huge demanding schedules, and her tour, has proved to both of them that this is something that is serious and that could last. It's really cemented their commitment to one another."