Couple each w/primary residence, just purchased new house. Help!

[Luca Mastrangelo]

Hi all. New to the forums here.  I just relocated to Cape Cod and my fiance and I just had an offer accepted on a house and need help figuring out what the best financing option is. 

I currently own a 2 family unit in CT that is fully rented.  Its got 10 years left on a 15 year mortgage. Its a conventional primary residence loan since it was owner occupied through 2014. 2015 was the first year that the property was fully rented.  

My fiance owns a 2 bedroom cape in CT that was her primary residence until we moved a couple months ago. It has 25/30 years left of a conventional loan.  The house is now currently rented under a lease for the next year.  

I'd like to keep my current 2 family since Im entering the accelerated portion of the mortgage pay off terms and also keep her 2 bedroom cape since its in a desirable location and should be easy to rent going forward. 

What should we do?  We will be getting married this year.  Will getting another "conventional" loan on our new primary residence be an issue?  Do we have to convert our individual former primary residence loans to commercial loans?  Should we be looking to sell this year to avoid capital gains?  What's the rule there, 2/5 years?  What else should we be thinking about??