You were probably too overexcited dating a lady, when you have to put on tight jeans. Then your sexual excitement continued for 1-2 hours. If it so perhaps the erection is not as strong as it was before. Too much tension and nervousness can bring to failure while trying to get an erection. There are some factors that deteriorate the situation and pregnancy hazard for instance.

How to get an erection? The number of alternatives is great. Use the link above to find the most effective one.