What is the best words to say to a relative who’s been trying to conceive since 14years back? :( The beloved couple is almost in their early 40's already.

If the couple do not mention anything about their intention to try for baby, it is best for you not to mention at all. Unless the couple is opened and bring it out first, you can share some of the tips to get pregnant, e.g. advise them to seek fertility specialist's help.