Four couples play at the Knights and Liars Bridge Club. The four guys are Alex, Bert, Carl and Dave. The four gals are Alice, Betty, Carol and Diane. It is known that four of the eight are liars and the other four are knights. From the statements they make below, determine who are in each of the four couples.
Alex: I married Betty.
Bert: Carol married Carl.
Carl: Dave married Betty.
Dave: Diane married Alex.
Alice: Alex married Carol.
Betty: I married Carl.
Carol: I married Alex.
Diane: Dave married Alice.