It may be a case of just not being ready yet. If you have an emotional connection, and it's acceptable to your partner not to be physical you can have a great relationship. Don't let anyone talk you into doing something you don't want to do. That could cause a bad memory you don't want, or screw up later relationships.
No, motivation levels fluctuate in everyone; even exercise fanatics find it hard to get motivated from time to time. So before you start, accept that there will be brief setbacks or times when you do not feel motivated.