Sure,
guy 2
is more likely because of when you would have possibly ovulated and the lack of ejaculation, but the consequences of being wrong about this would be pretty serious. Sperm can live a long time in a woman's system, and sometimes women ovulate early. If guy 1 had sperm in his pre-ejaculate and you did ovulate early (some women ovulate on day 8 of their cycle), it could be him. If you never do a DNA test, you will do a disservice to yourself, your child and both guys.