His Heart, Her Love by Jo Grafford

Patty Cason has always packed a few extra pounds. Even though she’s a successful college campus minister in L.A., this is her private struggle, something she’s tried to keep hidden from her friends and family while it slowly erodes her confidence and social life. It doesn’t help that she’s been privately crushing on Reverend Duke Carlson for months, a doctoral student who hardly seems to notice her existence.
When her campus co-pastor’s fiancee, Tanya, invites her to serve as her maid of honor at their wedding in Wyoming, Patty is forced to face her biggest fears all at once. Not only does she have to fly commercial to the Broken J Ranch, she ends up sitting next to Duke the entire trip, because he’s agreed to serve as best man.
To make matters even more stressful, Tanya and her fiancé have coaxed the painfully bashful minister into having Patty serve as his Plus One during the wedding festivities. Now, she’ll more or less be dating the guy of her dreams for the week. There’s only one problem with that plan: Duke has no idea he’s the guy of her dreams. What could possibly go wrong with an arrangement like that?