I think this was an above-average-quality made-for-TV movie that’s less than 20 yrs old, but I can’t remember the title or the actor’s names. I tried doing a words-search on Plot summaries in IMDB.com, but didn’t have any luck. Your help would be appreciated! 
Plot summary: A young woman con-artist needs to raise cash to get an old boyfriend out of trouble with a loan shark, so she decides to trick this really geeky guy into marrying her because he’s soon going to inherit money from a sick relative who’s expected to die real soon. The geeky guy runs a small town gas station/repair shop, and lives with a couple of older aunts who are suspicious of her. But she goes to the local doctor and switches urine samples with another woman so that she can claim to be pregnant. But the trick is on her, because it later turns out that she really is pregnant. She starts having seconds thoughts about what she’s doing to this guy. Then the loan shark guys get tired of waiting, they come after her, and the geeky guy protects her even after she confesses what’s really going on. In the end, she decides to stay with him and they live happily ever after…