Waltz in the Wilderness (Chaparral Hearts Book 1) by Kathleen Denly

Her mother died on the trail and her father was lost in sadness.  She camped with him while he looked for gold but he didn't find any.  He closes up camp and they go to San Franciso to stay with his half-brother.  They aren't the most welcomed by his wife but her Uncle is happy to see them.  However when she wakes up the next morning, her father is gone.  He didn't tell anyone where he was going, so she can't follow him...

Wild Heart Books let me read this book for review (thank you).  It has been published and you can get a copy now.

Her Aunt keeps inviting single men to dinner trying to get her married.  She's not interested.  Her father needs her.  She decides to go find him.  The last man invited over is close to her age and he knows she can't go alone.  He decides to tag along.  She's resentful at first but soon she knows she needs his protection.

She gets on a boat heading upriver.  The captain gives her some trouble until Mr. Clark shows up.  Soon they are off the boat and trying to find her father.  He's up in the woods, so they set off to find him with a home drawn map.  Before long, they have saved each others lives and set up camp to sleep.  She knows he's engaged but the longer they are together, the more she falls in love with him.  He's having the same problem.

When his fiance shows up, she has a confession, too...