No erection during foreplay. Insights.

Hi, I am a 25 year old man, with no prior sexual experience. Recently i came under a situation where i got an opportunity to make out with a girl. We like each other but she is engaged to someone else which we both have accepted. We both don't want to ruin any relation so we decided to only have foreplay but no intercourse. We made out twice and at both times i found no erection. I am a chronic masterbator and had no issue in achieving erection at that time, but this time it had happened and that too twice. I know i dont have any physical issue and it is rather mental, related to anxiety and reluctance of having sex as it will ruin our relationship. But given the fact that I'm a virgin with no prior sexual experience I'm worried if it is something Clinical and if it would effect me in future in my married life. Do i need a therapy. I'm really worried and would appreciate some insights.